ernie22golf

I have a 98 Trans Am with LS1 - Air Box - Only Pipes from Cats back with Automatic & 2.73 gear. What kind of et could I expect for the 1/4 mile. Are there any aftermarket exhaust systems that would produce more horsepower than only the pipes back from the cats? Thanks for your estimates of et's and the exhaust systems.
Thanks

kyles2000z

iTrader: (8)

mid-high 13's.

ive got the same exhaust, sounds badass IMO, and has to be the bst flowing (obviously), but i hear that more power is made with a catback system. i figured flow and hp gains were hand-in-hand, but im not too sure. i do know that the ls1's like a little backpressure from an exhaust, and thats why havin an aftermarket exhaust system gives more power gains, while !muffler is still the best flowing.

someone back me up tho, not too sure.

CaliboyTA

iTrader: (2)

probably mid 13's.

black01_WS6

iTrader: (13)

ya our cars need some kind of backpressure, thats why you see cars making good power with catbacks. now if you are running forced induction then its another story.

jmm98LS1

iTrader: (28)

Our cars don't need backpressure, that's a myth. It's all about keeping the exhaust velocity up. Backpressure is always bad, no matter what anyone tells you. If search works good enough (hit & miss lately) there's plenty of threads on this. Your car may "feel" faster with backpressure because it moves your powerband to lower rpms, but it's choking in the upper rpms. Take a look in the external section, you'll find all the info you need.

kyles2000z

iTrader: (8)

so does this mean that !muffler offers best flow AND power gains?

jmm98LS1

iTrader: (28)

With stock manifolds, cats, y-pipe and exhaust tubing......yeah, pretty close. Your main restrictions with !muffler would be the restrictive manifolds, cats, and flat y-pipe. Like I said, it's all about keeping velocity up with minimal restriction. You want the exhaust gas to stay hot and get out quick. Ideally you want longtube headers, a crossover that helps the scavenging process (basically pulling the exhaust gasses out), like a well designed "Y" merge or "X"/"H" pipe and a free flowing muffler(s) or none at all if you like being deaf . Like I said, poke around in the external section and learn for weeks......

davered00ss

iTrader: (4)

13.4

Travis99LS1

iTrader: (2)

I pretty much have the same thing as you do...a whisper lid, and a cutout, and my best 1/4 is 13.1..everycar is different, the only real way to know is go to a track and run your car

nelson1100

iTrader: (1)

with a 240 pound guy half tank of 94 octane gas with an auto 13.4 but its a low miles car.

Rebelord

iTrader: (2)

With a lid and !muffler..i say 13.4-13.6@103-106. My '01 bone stock a4 w/2.73s ran 14.0@103. I put a lid and !muffler same night and ran 13.4s. You should be around there. BTW, put it in D when you stage, but you'll still be in 2nd gear when you go through the traps. Seems like it takes it forever to change gears.

Ski

davered00ss

iTrader: (4)

I have seen several stock auto's, and they all run about 13.4

bowtieforpower

iTrader: (2)

thats funny because i was there and i dont remember you swapping out those "that night" and btw I ran the 13.4, not you......