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So one of the reasons I don't drive my Camaro much is because of how loud it is. I think it sounds great and I really like the sound it's acceleration but it really gets the attention of anyone within sight. I had a recent encounter with a real A hole that lived in my subdivision that helped open my eyes to how prejudice people will be against you (and how fast they think you were going) just because you have a loud exhaust. Now I want to be clear, I'm not looking for a way to speed or drive aggressively and be less noticeable, I'm looking for a way to drive like a normal person and no longer have people upset because your car is loud. I'm sure we all have our own personal experience with the matter.
Anyway, I've read that the Bola XS, Walker stainless Quiet-flow and Dynomax Super Turbo are good options for quiet exhaust without sacrificing power. Does anybody have experience with those mufflers or can they suggest a factory muffler from some performance car that flows well? Does anybody have links to muffler dB tests? I'm even open to stacking mufflers together since some like the Borla XS are fairly short.
Dynomax has always been on the quiet side with good flow, but still plenty loud at WOT. Same goes for most glass packed mufflers until the packing breaks down.
In the link below they DID NOT tune for each muffler, so what you have here is what muffler made the most power with the car’s existing tune. So, you don’t really know if a drop in power from one muffler to the next was due to the increased flow from the muffler causing the engine to run lean, or if it actually was restricting flow. The real tip off is that the straight pipe, no muffler, made less power than with a muffler.
Regardless, note that the least power with DUAL mufflers was the capped up Warlock at 366.3 HP and the most powerful capped up muffler was the Bassani at 373.7 horses which is a whopping 7.4 RWHP. Actually, the Bassani and the Hooker were very peaky and the Borla XS had more power under the curve. So, take the power differences with a grain of salt - what I thought was cool though was the sound level test. http://www.mustangandfords.com/parts...omparison-test
Keep in mind you need approximately 2.2cfm per horsepower in order to not see a reduction in power. If the Borla XS can meet your power needs, then it’s hard to beat for quiet performance.
The Borla XS is really similar to the SLP 2otL in some configs. Straight through design, center 3" inlet, dual 2.5" out. But you can get it in a bunch of different layouts.
Its crazy how some of those mufflers are nearly the quietest of the bunch at idle, yet blow out the SPL meter at WOT.
Except, my GTA idles around 91db, and god knows how loud it is at full song cause I've never heard anyone else whale on it while I was not in the car.
Thanks for posting the links and experiences guys, exactly what I was hoping to get. I'm thinking of buying two of the Borla Pro XS mufflers that are shorter, single inlet/outlet that enter and exit opposite corners and hooking them in series. They are reversible so I will have them set up so the exhaust flow has to change directions twice. I would think that would really help to quiet an exhaust down. I had read a thread or to across some other car boards where members had done that for sleeper cars. Sound fine or like it would really hamper flow?
I had MagnaFlow magna packs and it was too loud, switched to Super Turbos and it quieted it down a lot. I can't seem to post a video here with the sound.
I had MagnaFlow magna packs and it was too loud, switched to Super Turbos and it quieted it down a lot. I can't seem to post a video here with the sound.
Just throwing this out, because there isn't a whole lot of room under a 3rd gen to do this, but I bet it would be possible. My BMW has a V8 in it, a sleeper engine. What the factory did was put small silencers right after each exhaust manifolds, and then another single silencer where the dual exhaust feeds in/out its very flat. I'm guessing this is some sort of X-pipe internally. From there it connects to two normal mufflers hanging under the trunk, again similar to ours. At low RPM's everything is closed up and the car is quiet as a cat. Once you get over 2000 or 3000 rpm, vacuum opens up a dump, and the roaring sound of a V8 comes to life, surprising any passenger who has never rode in your car before.
Last edited by LiquidBlue; Jan 31, 2020 at 10:06 AM.
A few things that might help:
- late 3rd gen and 4th gen mufflers got pretty good from the factory. On my '97 WS6 I cut the intermediate pipe right after the axle and welded in a flange so I could drop the muffler and tailpipes off of the car by removing 3 bolts. On that car running a fairly mild combination with enough N2O to run 11.0's @ 119 I was never able to document ANY difference with and without the muffler/tailpipes, and I even tried back to back runs- make a pass, come back, drop the muffler in the pits and make another pass and I'd run the same times.
- The closer you put things to the engine the more it affects power. There was a Pontiac forum member back in the day that wrote an article about trying to get a Pontiac wagon drag car quiet and he was able to show that you could make your exhaust smaller as you went further back without losing power but making the car significantly quieter. He ended up running the same times as headers into 3" dual turndowns (might have been 3.5") as he did with headers into a 3" X pipe (again, might have been 3.5", it's been a while), 3" mufflers (the "Hemi" dynomax super turbos) and 2.25" tailpipes in something powered by a 500some hp 455 pontiac that sounded like a stock car. When messing with these kinds of things remember that straight pipes flow more than anything else, and mufflers flow the least, so neck down after the mufflers and other restrictions.
- My favorite F-body exhaust has been a 3" intermediate pipe into a 3" dynomax ultraflow welded (they sound much tamer than anything else, and check the published flow numbers, there is an offset center config that flows more than the rest) and a single 3" tailpipe. It's not super quiet, but even with a fairly serious engine it sounds a lot like a stock exhaust on these cars and I'd bet flows enough for 99% of the engines on this board. I've had that set up on 3 different cars and been happy with it, and the typical no comression, gm Goodwrench 350 with nothing done to it + small flowtech headers and a flowmaster 80series will drown it out from 20-30' away. I finally put an electric cutout on my current one because everyone's car, truck and moped was louder than mine and I wanted to have some fun. That same setup with a 2.5" tailpipe (maybe even a 2.25") could be completely stealth without loosing much if any power.
I'm guessing that he could step down the diameter the further he got from the engine because the exhaust gas was cooling down and the smaller diameter actually increased the speed of the exhaust gasses while dampening the sound.
