i have a 1992 chevy fullsize truck with a mildly built TPI motor, 355 91 z28, 212-218 264-270 487-495 110 comp cam "would like to go bigger someday" , comp cams 1.52 roller tip rockers, edelbrok base, ported slps, ported plenum, bbk 52mm, 24lbs, afpr, hypert flat tops, this wenter ill be lookin for some afrs or truck flow heads, i have some coated headers i need to get put on and when i do so im goin to have the exhaust redone, what would be best for my truck........ 2.5" cross pipe to a 3" high-flow cat to a 3" in/out magnaflow muff single or would it be worth it to spend the extra and do a dual 3" cat 3" magnaflow setup??? when i do this i m goin to go with the bigger magnaflows to keep the sound down, also i want to run it like the ford lighnings and bring them out on a 45 in front of the back passenger tire!! so what do you all think??

 

you definitely dont need dual 3" but hey go for it if you have the clearance and money

 

If anything go dual 2.5". Single 3" might choke the motor but dual 3" is way to big. Even if you did "go bigger" down the road, unless that motor is making 500hp dual 3" is overkill on the wallet and the motor. You will lose power with 3" duals.

 

I really wish someone would post real world results of power being lost from exhausts being "Too big."

"1 test is worth 1,000 expert opinions."

 

ok so if i want to just do a single pipe exhaust, is there anythin bigger then 3" i could do? i want this setup to be the last one i have to do, so i dont want to be choking the motor, but i also dotn want to losse low end. would the 2.5" cross pipe be fine or should i go bigger with that to?

 

I have a 1500 as well....

... if you went with a single pipe, I'd take your restriction.... (Y pipe)....... cut it off, and beat you with it!

 

u have a 1500 with a tpi in it? if so what all do you have done to it? what exhaust r u runnin? what exhaust do you think i should run then?

 

I am a dual exhaust fan myself, I have a 79 454 pickup, which had dual exhaust originally so it was a no brainer, I jumped to 3 inch exhaust on that and noticed a rather large improvement over the stock 2 1/2 system from the factory, my truck picked up 3 tenths, good mufflers were also part of that gain,,,I had to rejet the carb to compensate. On your truck with the smaller motor I am not to sure the 3 inch dual would help or not, plus if you have to stay emission compliant there is the extra cost of another converter etc....On a truck there is so much room you can do just about anything you want under there, just a matter of how much you want to spend. I would personally go with duals on a truck, but thats just me, goodluck,,,,Larry.

 

Sorry for the confusion - I still have my TBI on it, but I did jump to a dual 2.5 setup.

Single exhausts are for one of three types of engine setups in my opinion - 4 bangers, inline 6's, or single turbo cars like a supra.

If you have two banks to an engine, don't force them to compete for space in a single pipe at a single y joint.

 

They do have formulas for HP at RPM ranges vs. pipe size. I don't think anyone here knows them though.

You can tune an exhaust, and a properly tuned one will give you a little more power. Maybe a huge exhaust just doesnt give you that little more power, but doesn't take away power.


I figure the header pipes do the scavenging and then use big *** pipes to get the exhaust the hell outta the system.

 

well i have one 3" highflow cat im runnin now.....how well will this flow.......3" mandel bent cross pipe to a 3" cat to a 3.5" dynomax ultra flo round muff and then 45 out in front of the back tire, wont be much pipe with my std cad short bed! i just dont want any popping "back rap" at all.....i hate that!! how loud will this be...i dont wnat to be louder then what i have now.....40 flowmaster 3" in dual 2.25 out 3" cat...