surely i figure just a straight pipe is too loud for the db limits at some tracks. so what else are u running on there? any kind of silencers or cherry bombs/glass packs?

 

Use a straight through "bomb" style muffled like a Dynomax turbo tube, etc. to take the high end and rasp out. Use larger tubing size on the exhaust, at least 2.25", as small stuff gets raspy too. This should knock a straight pipe at WOT down into the low to mid 90s db range and not rob much power. Still a lot for the street but fine for most track sound limits.

Stay away from the Cherry Bomb brand as they have a power robbing reputation. It think it has to do with the direction of the perforations causing issues.

 

Burns makes a repackable bomb that's 3.5 inches in diameter as opposed to the 4 inches of the Dynomax and Magnaflow's I've seen.

You could also look into Pete Webers "expansion chamber" looking muff's - alot of formula cars and sports racers use them - but I don't know how they'd work on the end of a long exhaust.

Scott, who's in the low-mid 90's with a Magnaflow resonator and a Dr Gas muffler at the back...

 

here's the ticket; effective and cheap (this is on a H1 LS motor):

-KOS header, 4-1 , with 2.5" collector.
-2.5" flex connector
-2.5" piping leading to a JC Whitney "cherry bomb". weld in the cherry bomb BACKWARDS; that is, with the little perfs facing the wrong way
-45 degree turndown under the car.

this setup is too loud for street use, but passes noise regs at all tracks i have been to.

AND, it made only 3 less total HP (up around 8k rpm) than a straight 2.5" pipe on the dyno during tuning.

and, best of all, the components are cheap cheap from JC Whitney.

good luck

 

todd, the cherry bomb perf's are supposed to "open" towards the front of the kaa, correct? so weld it in so they're facing backwards? that makes sense that it would not restrict the exhaust flow as much, but will it really help out with sound like that?

 

hi hunter.

i welded mine in backwards; the perfs are opening pointing towards the outlet; therefore not disrupting the exhaust flow much.

and it definitely knocks the sound way down compared to no muff. much quieter and "better" sounding. my LS seems to have a really low, power type tone to it.

 

so all u have in there is one glass pack bass ackwards and that helps out a lot? which one did u get from jc whitney... they have a couple different ones, and sizes?

thanks,
Hunter

 

i don't remember which one, other than it is about 4"-5" in outside, dia, is 2-1/2" pipe inlet/outlet, and is about 30" long or so. it was "aluminized". the flex connector was stainless steel braided.

HTH

 

I run a dynomax bullet, the pipe stops just short of the fuul cell and there is a turnable tip to duck the "sound sniffers". THe system worked great and I never failed sound, but I was going def in any race longer then 15 min. I added another bullet, prob lost some power, but now can hear myself think...

 

I have a 2 1/4 pipe leading to a Supertrapp, which is adjustable. I usually drive to the track with 4 discs, then remove them all when I get there. I've never dyno tested, but no discs or cap clearly flows better than 4 discs. The most discs you can put in is 10. So far, no problems on the track (got pulled over once on the street though). I've noticed a few high-dollar cars using them if that's any indicator.

 

Todd,
Where did you get the collector from? Checked out JCbiteme, and they don't list those. I have the header pipes, but do not have a collector. 4-1, 1.375" to 2.25".

 

sorry; i guess i wasn't clear in my first post:

the KOS race header is a 4 into 1 design, ending in a 2-1/2" flanged collector. so it is all one piece, welded. I really like its fit, performance, and price...

i only bought the flex connector and muffler from JC W. got the rest of the pipe and 45 deg turndown from PeP Boyz

 

Just had the local Meineke fab up a system (if only I had a welder <G&gt from 2.5" and a pair of their spiral core mufflers mounted end to end with a 3" section of pipe between them. We dumped along side of the fuel tank. Loud is not the word here-this thing can be heard 3 blocks away at full song-but it is track legal. I did measure the dB level and it is over 100 at 10 feet, but will comply at 50 feet. The car has a definite 'seat of the pants' vibration level to it but not objectionable. A single "cherry Bomb" or dynoMax bullet will probably be ok except at tracks like Lime Rock with their 90dB max.


Modified by jc836 at 7:03 PM 6/13/2003

 

my hybrid w/ testpipe has been noted at 91 db... at WOT.

 

How would a high flow cat right after the header, followed by a straight pipe to the rear of the car compare to the straight pipe to a glass pack setup? Would it be much louder?