1st Aurora with Borlas

[Custom88]

well, I've kept it a 'secret' for long enough that I was going to swap out my stock mufflers for some Borlas. I ordered them last week and got them installed today. I'm not too happy with the sound however. When I installed Borla mufflers on the Riviera they were very deep sounding. The borla's don't sound as impressive on the 3.5 though. at idle they're as quiet as stock and there's a slight drone at around 70 MPH. (highway cruising speed which I do 4 days a week. ) When you gun it it's real loud up until 4,000 RPM then the exhaust falls almost silent again. I don't know if it's the engine displacement that makes it sound like this, or what.. not sure really. I have heard that mufflers have to "break in" and after a few thousand miles will start to sound better. Hopefully that'll be the case here? I was expecting a deeper sound. Luckily these mufflers aren't too loud though.

They're the Borla PRO XS mufflers that retail for $150. I got them on Ebay for $87 each though. The installation ran $40. (they were welded on.) These Borla's weigh about half as much as the stock mufflers and they're basically the same size!

stock mufflers


Stock mufflers mounted


New Borla Mufflers


New Borla's.. they're a straigh-through design. You can see from one end straight through to the other. The stock mufflers have several 180* bends in them


Borla PRO XS mufflers mounted



media.putfile.com/Borlashortstar
In the first clip, I have the windows down and start off at 1/8 throttle. I then gun it to go WOT. In the second clip I'm only going half throttle toward the end. In the last clip of this video, I went full throttle at around 20 MPH. the windows were up. The rattling sound you hear is from the stock mufflers in my trunk..

media.putfile.com/auroraborla
This is a video of the exhaust from outside of the car

[ahh00]

I can't seem to get the clips to play. Would you be able to email them to me? I also have an 01 with the shortstar and REALLY REALLY REALLY want to know how it sounds with [glow=red,2,300]aftermarket exhaust[/glow].

[erw38]

Congrats on the new exhaust!

[Aurora40]

I can't get them to play either. However, it looks nice. Sorry you don't like the sound of them. Every engine is different, so good sound on the 3800 might not mean good sound on the shortstar. At least you didn't spend a lot on them. I believe the "break-in" comes from the glass matting getting seated and more compressed after driving a bit. I believe Borla's use that kind of matting, so they probably will break in some.

Does the car seem to have much more punch to it?

[Custom88]

the clips have to fully download before they'll play. I haven't noticed much of a difference performance wise I don't think. It's hard to tell so far. It feels a little quicker but it could just be in my head. For those of you who can't get the videos to play, I made an MP3 (compressed) of the second video.
media.putfile.com/auroraborlaexhaust

[JimW]

I couldnt get the videos to work, but the mp3 works, thanks.

Overall, I think it sounds ok. The 3.5 is a pretty conservative engine, all things considered the Borlas sound OK. I doubt it would sound any better if you took the resonator off, so dont do that.

It sounds better then stock..heh.

[Custom88]

alright everyone,if the first videos didn't work, here is the first video in a different format. Let me know if it works for you!

EDIT: my connection is so slow during upload, that my upload timed out causing the video to be imcomplete. I was forced to split it into two different sections.
media.putfile.com/shortstarborla
media.putfile.com/shortstarborla2

Jim, you're right, it sounds ok. It doesn't sound great, but it doesn't sound bad, either. I was hoping it'd sound like the Riviera did (great.) They're the same mufflers even. lol. Guess Bob's right, can't expect a different engine to sound similar.

I'll just have to keep in mind that stock there was no exhaust note heard inside the cabin at all. now there is quite a bit at low throttle application. Right off the line it has a growl that eventually fades.. under heavy throttle it's pretty quiet though. If you turn the volume up a bit you can hear what I mean.

EDIT 2:
I found a sheet that came with my mufflers. It shows their construction.

3 pounds of fiberglass and .4 pounds of steal wool. hmmm

[mission008]

the exhaust looks good, except wouldn't you need to have all of the exhaust piping (cat back) changed out for the mufflers to sound as good as they can?

[BNICOV]

Sounds pretty cool. Mission, the mufflers sound pretty much like they can, the only different thing would be to take out the resonator but there are differing opinions on that.

[macadamiaman]

I hear you - I don't like the sound so much. Even borderline ricey, but hey what can you expect from a V6. They don't sound BAD, just not special and I'd prefer the stock

The welding looks like it's already rusting - are the borlas stainless? I heard there's always problems welding with stainless steel (as the pipes are on your Aurora)... what do you mean by hmmm?

[Aurora40]

Hey Dan, the first two you posted come back with an invalid codec. I believe they are corrupted or something. It isn't just waiting for it to download.

On the audio clip, that sounds fine to me. It doesn't sound that different than stock except that it is louder. With no load, though, they don't seem to sound as good. My car doesn't sound that awesome when I goose it in P/N. Under load the sound gets a lot better though.

Your in-car video sounds to me a lot like my in-car video. I dunno, I can't hear the difference. It sounds alright to me. Some video of the car driving away from outside would help, though. And maybe an in-car where it runs through the range more than once? I dunno, it was hard to really appreciate what it sounds like.

Edit: I listened to them a bit more and a bit more closely. On the audio/stationary clip, when you blip the gas there is like an initial growl, but then more of a mechanical sound. It's hard to say if that's the exhaust or just that you are in the car? That part doesn't sound so great but perhaps under load it is different.

On the 2nd part of the video, there does seem to be a bit of a booming around 4500 rpm or so that then gets quieter after that. Perhaps this is some second-order resonance or whatever the heck it would be called at twice the normal resonant frequency (usually around 2 grand or so for most cars)? Perhaps some higher-order frequency the mufflers used to take care of? I dunno. It isn't bad, though.

Do you think you will keep them?

That fiberglass and steel wool is the packing that absorbs sound. I'm surprised there is only 3.4 pounds of packing, I'd think it would have been a lot more than that.

[Custom88]

Honesty, I really miss the stock sound. I was expecting so much better sound than what I got. The largest dissapointment was when I started the engine cold and walked away from the car while it warmed up. It sounds really bad from behind.. almost like a 'rice' 4 cylinder engine. The shop mutiliated my stock mufflers though so I really can't go back to them. Under light throttle the mufflers are very loud. Get on it a little bit and they quiet down until you can't hear them. It's so odd. I'm almost embarassed to drive it now! I don't know what to do honestly. I can't believe there's such a huge difference between how these sounded on the riv, and how they sound on the 3.5. The only difference in the setup was 1. the engine 2. the riv's dual pipes were upgraded to 2.25". With the aurora I kept them at 1.75." Why are they so loud and full of drone under light load/low RPM's? It sounds fine when you get on it.. ideas?

[95mushroom]

They don't sound too bad IMO. I was expecting more of a 350Z especially because there basically the same DOHC 3.5L V6. Or even a 3-series sound.

Could be worse though...

Betcha the piping size has to do with it.

[Aurora40]

1.75" ?? I really need to buy a caliper and measure my dang exhaust... I could have sworn it was like 2.25" stock and 2.5" stock before the Y. 1.75" is like the size of the single exhaust on my Nissan I thought?

I also can't figure out the Corvette's exhaust. So many replacements are 2.5", but the stock seems bigger than the 2.5" Corsa on the Aurora is (or I thought it is 2.5" anyway).

[macadamiaman]

There's a huge difference between 2.25" and 1.75" piping. If you can't go back to the old mufflers, upgrade the piping. Then again there is a huge difference between the 3800 S/C and the 3.5L shortstar... too many variables to compare to a Riviera, right? But yeah it does sound kinda ricey, like you lost a couple cylinders.

[Custom88]

I did a bit more looking and found that the mufflers I had on the riviera were actually the TURBO mufflers, not the PRO XS. the Turbo's are 20" long mufflers and the PRO XS's are 14." I'm sure that the combination of the larger piping, and longer muffler made a significant difference in the sound output. That is why my Riviera had to be upgraded to the 2.25" piping. The inlet/outlet of the turbo muffler was 2.5." the inlet/outlet of the PRO XS is 2."

Bob, the exhaust shop said my stock piping was 1.75" after the split. Before the split it is 2.25" if I remember him correctly. I'll wait a bit and see if these mufflers 'break-in' to sound better. I sure hope so.

[Aurora40]

But on your muffler spec sheet, it seems to say the internal diameter of the two end pipes are 2"?

[Custom88]

the exhaust guy used an adapter from 1.75" to 2" to accomodate the new mufflers.

[Custom88]

I found a site online that said that Borla mufflers can take up to 4,000 miles to completely break in. They do sound a little bit deeper than they did yesterday. I think I'll just wait and see how they turn out. I'll post clips in a few weeks, or months for an update.

[auroralover]

Dan, I think they sound great. Don't beat yourself up yet, give them some time. BTW, where did you get the spoiler for your car? Showed my wife a pic of yours and now she wants one for hers.

[Custom88]

thanks! I got the spoiler from www.spoilers4less.com

[scottydl]

I think they sound fine, although I never heard the stock exhaust. I think you will notice a difference after break-in... the Dynomax ST's on my Executive are definitely louder now than when I first had my dual exhaust installed.

[stevensolds]

Just drive around all the time to get them broken in. Thats what i did...parked it all of december-january (only 675 miles during that time) and then spring finally came and i drove 2k miles in like 2 months. Now that i look back on vids, my dynomax's sounded really RICEY when i first drove em home. Oh well. Maybe your will smooth out.

[macadamiaman]

Maybe next time buy some used mufflers - already broken in

[Custom88]

ok, does anyone else have drone after replacing their mufflers? between 45 and 60 MPH I get pretty loud engine drone that I can hear in the cabin. If I'm going over 70 MPH it goes away. If I accelerate and leave it in 2nd gear and get the RPM's up, the engine sounds great above 3,000 RPM. as the RPM's get lower the exhaust note gets louder and louder. The drone is loudest at 1,800 RPM. (it's louder on deceleration than acceleration.) WTF can I do to quiet this drone down? I think that's driving me nuts more than anything!

[Aurora40]

sounds like resonance. usually that's when the exhaust is louder at a lower rpm while cruising, but opening it up makes it go away. My 'vette does this to a fair degree when cruising on the highway. It's louder and dronier in 6th than if you drop it down to 5th.

Other than suck it up or make changes to your exhaust, I'm not sure there is too much else to do... :-\

[scottydl]

Yep, same on my Executive. There is substansial drone crusing around 50-60 mph (unsure of the RPM's), but goes away if I really get on the hammer. Since aftermarket mufflers are made to install on so many different engines, I think it'd be fairly impossible for Borla (or anyone else) to make a muffler that keeps an even tone across all applications.

[Custom88]

I need to make an update so those who were considering exhaust on the 3.5 can get some insight after I've given the mufflers a week to break in. The sound has gotten a lot deeper than what it was at first, and it's really starting to grow on me. Before I could only hear the exhaust at lower throttle and on deceleration. Now, at idle it's almost silent in exception to a little burble that you can hear from behind, at low throttle it's deep and throaty, on midrange throttle it's pretty quiet, but when you go heavy throttle so that it shifts over 3,500 RPM it roars pretty good. The engine actually sounds powerful now. lol. I can see how gas mileage can go down with adding exhaust now, I just love how it sounds when you get on it!

[Aurora40]

LOL, glad to hear you are liking it more Dan! You'll have to make some more sound clips...

[scottydl]

custom88 said:

I can see how gas mileage can go down with adding exhaust now, I just love how it sounds when you get on it!

Yeah steven, I know what you mea..... oops your comment made me think you were someone else! ;D

Glad to hear it's sounding better as expected. I'd imagine more break-in time will only open the sound up even more.