Chevy Vortec 350 exhaust question

[Scott A.]

My tow vehicle (97 Chevy Tahoe 5.7 4wd w/146k) lost half of its exhaust on the road this weekend. I've had this truck for over 9 years now and would like a little more towing power out of it. Looking at the shorty headers and off road pipe kits & cat back systems to replace what's left....is this motor worth putting headers on to gain a few hp's? Some are claiming 20+ hp gains in the 1500-3500 range (which is where it likes to be when pulling about 6000 lbs). It has (2) cat's on it + (4) o2 sensors - looks like with the off road kit you have to be creative to trick the ecm to believe it still has the cat's.

I was considering a gear ratio change too (has 3.42's right now), but since I have to do something about the exhaust now, and didn't really want to effect the gas mileage (pulls around 13 towing, 19 no tow), maybe the complete exhaust kit might be the way to go? Anybody else experiment with these motors?

 

[cruzn57]

any headers you install.......

will more efficient than stock manifolds. and you will see/ feel an improvement.
to obtain the most from your truck, you need a free flowing exhaust system, no less than 2 1/4in dia, 2 1/2 is normally used.
personally I'd stay away from flow masters as I feel their to loud, walker dyno max have good sound control and very low back pressure.
a cross over or balance tube will help mid range torque.
header length will be irrelevant because you are running a full exhaust system.
stick with smallest tube primary headers you can find, to help low end power. coated headers will last longer.
where I used to work, we ran chevy 5.7 roller motors to 200K mi, with no issues.

 

[t-typinator]

What i love about my 98 Silverado with the same motor is how quiet it is,I actually take it on long trips instead of my cars.
Headers, off road h pipe,+ cat back is going to make it alot louder + give it alot of drone,especially under a load, like when towing.
That would irritate me,+ would not like the truck as much, before you do it i would definetly look into how loud it makes it.I would suggest maybe just going with high flow cats to free up a few hp. Unless you don't mind loud stinky trucks, then i'd say lose the cats,go headers + flowmasters.

 

[TexasT]

Mine is a little older(94), longer(burb), and a few more miles(275). Mine had the muffler nipple break off the muffler. I bought a 3" cat back flowmaster setup. It has worked great for at least 70k. Louder but not obnoxious. It has a big 3chamber muffler and the pipe turns out and down after the pass rear tire. I think it was about $300 shipped from Summit a few years back. I like it.

 

[83turbomon]

I got a 93 suburban, with 192k miles on it. alot of the 90s trucks have large resonators on them.... take em off to free up a little mid range power and replace it with some dryer tubing... and if it has a plastic air channel in the fender, take that out too. as for exhaust Im more for power than sound. Id go with a nice magnaflow setup channeled and a crossover to a nice tip... any tip should work really. also a high flow cat...

 

[Scott A.]

If I go with headers, off road pipes, etc, how do you go about re-tuning these creatures? The truck had a stock exhaust except for a flowmaster muffler...wasn't too loud but the muffler sure rotted pretty good after (4) years.

 

[Chuck Leeper]

My $.02...

Did some back to back tests on the 96 Subby I had...Stock exhaust, vs shorty headers.... After many hrs of labor, results were non exsistent. The dyno reading tolerances were more than the gains..The tests were so inconclusive, the article was not published.