Best exhaust for a 98/99 Vortec 350

[texlurch]

So I have been studying, and trying to decide which way to go for the best sound/performance/MPG on my truck. Priority is MPG, then performance, sound being last.

It now has dual Flowmaster Delta Flows , dumped, because I didn't want all the noise of the 40 series.

I plan to get a set of the Thorley headers and y-pipe, either new high flow cats or no cats/O2 sims (truck has 105000 miles now)

Measuring my stock piping it looks to be 1-7/8 OD (2" at the very most), which seems really small for a 5.7. Truck was all stock when I got it.

I plan to go to dual 2-1/4" from the Thorley y-pipes back, with either a x-pipe or a straight crossover. The way the cats are staggered the x would have to go behind the cats. If I gut them and rearrange, then the x can go right in front of them. I don't think they will light off if I move them too far back. Everything I have read points to the x being better performance-wise.

So far as MPG, is there anything PROVEN to be better than the Flows? I didn't see any increase or decrease when I cut off the stock muffler and put them on. Sounds better tho! :crazy:

Not really loooking for a real loud system, it is pretty OK now so far as noise. I hate a drone on the hwy.

Suggestions are cheerfully appreciated! :D

[texlurch]

amazing. No opinions? Not even the usual "Flowmasters suck!" :D

Guess I will have to be the guinea pig for a change! :crazy:

[97Chebbie]

You could probably try Magnaflows or a different series Flowmaster. Corsa would prolly be good too, but they only sell catback systems, but there really isn't any difference in performance between true dual and single in dual out systems unless you have some wild engine mods like a supercharger. The optimum size for true duals would be 2.25-2.5". As far as all that BS about Flowmasters sucking so much. I find it hard to believe that a company w/ such a "sucky" product would sell so well and be used on so many competition level cars. :dunno: I think Flows sound better then most exhaust IMHO and don't really care as much about getting a few more HP out of supposedly much better flowing mufflers. However, I might be switching to Dynomax Bullet mufflers for a louder sound eventually, but saving for college is a bigger priority right now. :bawl: Hope this helps. :D

[geno96Z71]

I'm also looking at a complete exhaust system to improve performance and mileage, but am considering some different components. I'm looking at Edelbrock's stainless headers and going with some type of 2.5" dual exhaust setup -also with Flowmasters' Detla series mufflers.

As far as my past experience with Flowmasters, I made the mistake of putting 2-chamber 2.5" cans under my '72 Firebird (typical musclecar setup). That setup droned like a 2-story beehive about to attack- so I'd definitely skip the 40 series units. The 50 series deltas seem to be the better bet (good sound, but not as noisy). My biggest issue so far is figuring out how and where I want the crossover pipe.

Geno

[Stevo]

i put some thrush packs on mine i think they are 24 inch long? put they don't really crack at all and they have agood tone to them not to loud and it sounds good outside. I too am not to concerned over a few hp some mufflers make.

[texlurch]

Thanks for the replies!

My main concern is the small diameter of the stock pipes. I also have looked at the shorty headers, but from my experience they gain very little. I also like the Thorley tri-y design for torque, and the fact they come with bigger y-pipes back to the cats.

I have pretty much decided to !the cats, and install an x just in front of them, where the head pipes come back together. Then I can install a straight piece of pipe thru each cat, leaving the illusion of them still being installed for the state inspection eyeballs. O2 sims will keep the SES light happy, which is all I need to pass the emmisions check around here :D

I have run plenty of Flowmasters on different projects over the years, just figured I would see what else (better/newer) is out there.

The easiest fix for the pipe would be to find a 1-ton BB in the JY, they have 2-3/4 or 2-1/2 pipe on them, run the same way (thru the same size cats :think: ).. at least on my buddies 2000 OBS that I crawled under... (he wouldn't let me take my sawzall to it tho! :D )

Guess I will start gathering parts and see what happens! :idiot:

[dfarr]

I have a fm 70 series in 3", had to add a borla in front as a resonator so i could talk on the highway, check out v6z24.com for a comparison.

[Southern Mudder]

My has cats and straights on his 96 and it sounds good.He has the stock manifolds and true 2 1/2 inch duals with some hi-flow cats and it as loud as mine with true duals, no cats and 18 inch glasspacks.