cat-back exhaust doe's it lose power ? please help

================================= Seems the problem is they go too big on the pipes. Bigger is not always better. You can loose low end torque by using too big of exaust. Duel 3" exaust is for drag racing(wide open throttle, max RPM, tuned engine to high RPM ) for example. I dont know the secret formula, but I think your best bet would be stock sized pipe, mandrel bent, going through a high flow cat and straight through type muffler like a Magna-flow. If you must go duel, I would consider much smaller pipe. GL

scott i was thinking of using a 2 1/4 inch duel system i was never going to use 3" pipe. to get specific one freind has a 3" cat back mandrel bent with a 40 series flowmaster on his 4.3 reg/cab s/b. i went for a ride in it before and after he had his exhaust done, and there was a noticeable loss of power through out the rpm band lost botom and top end...... another freind 5.3 reg/cab s/b, just replaced muffler with flowmaster also complained of lost power. and a couple other guy's i've asked have said the same. just dont make sense to me any help would be appreciated. thanks again.

Yep, 3" on a 4.3L is way too big. I think stock is 2 1/4. As an example I would probably use stock size mandrel bent pipe going through a high flow cat and straight through type muffler(flowmaster is not a straight through type btw, they sound good though, but a bit loud for my taste.) As far as going duel, well your on your own. I hate to say it but sounds like Chevy has their exaust tuned fairly well judging from your friends trucks. I do think you are wasting your time going with a duel cat back if you are expecting performance gains from it. I could be wrong, but I would like to see HP/torque readings from a dyno to prove me wrong. There are way too many people out there who think there truck is faster cause it sounds louder, or the ad said "up to 20 more HP!",know what I mean?

Please no flames unless you have before and after dyno readings to back them up. :) And try to remember we are looking for drivability HP, not drag racing 6000 RPM crap. Well I am anyway.

I'm with Scott, I want to put dual flows on my truck mostly for the sound, now if I gain anything great. it not oh well.. I just hope I don't loose. but i've always read, smaller pipes produce more low end hp/torque and larger pipes produce more highend hp/torque.. check with your local exhaust guy and see what he says..

Adair

In a few horsepower books I've read, they've all denounced the "less backpressure = less lowend power" thing.

I installed a 3" single cat back (Corsa) behind my old 5.3 Avalanche. It had as much backpressure as a straight pipe. That's all it really was.

I had "noticeable" gains in the upper rpm range. Nothing big, just noticeable. I swapped my stocker back on before I traded it in - the lowend stayed the same, but anything above 2K was lacking.

I'm wondering if the gains found from a catback like this (apparently

-marc

I've heard a lot of bad things about flowmasters performance.

More often than not, they're called "Chokemasters".

:(

-marc

mark i was planning on using borla's any way. also did you notice if there was an increase in milage ?. do yuo guys think a x or h pipe would help if so which one is better. thanks again.

David,

I installed a 3" cat-back Flowmaster Force II system a few months ago on my '95 w/ 350 TBI. The improvement in flow is substantial over stock. My mileage increased a little, but not much. I would have loved to go with Borla's, but price limited me to the Flowmasters. (cost me around $212 from summitracing.com)

Cheers, KB