Formula350Scott

iTrader: (3)

I'm running a p600b running 10#s of boost with ported stock heads and a HSR intake on a 350. Right now i have Hooker 1 5/8ths long tubes into a dual 3inch y pipe to an SLP loudmouth exhaust with the resonator and a dynomax bullet muffler. I'm thinking i could definitely benefit from 1 3/4s inch headers but i dont know about the rest of the exhaust. I need some opinions.

xpndbl3

iTrader: (5)

mufflex 4" with dynomax ultra-flo muffler or true duals with dumps

joeblue83

iTrader: (8)

Everyone on this board always recommends a 4 inch exhaust, why? If I were you I would do a 3 inch exhaust with 1 3/4 headers, and a cut out. If you didn't want to do that, the max size I would go is 3.5 inches. My
By the way I run a 3 inch catback with 1 5/8 shorties. When I borrowed my friends LT 1 5/8's with no exhaust hooked up I only gained 10 horse and .1 in the quarter. In my mind its not worth it. Try and maintain as much ground clearance as possible if its a street car.

lt1z350

iTrader: (2)

went from a 3 inch to 4 inch and was a seat of the pants change on a 383 in a lt1. Never got a chance to dyno compare but it was a solid 3 tenths with not much weather change in the quarter and I think it was 2 mph. Any time you get a set of the pants gain it is pretty good. For that reason I went straight to a 4 inch on my l98. Really all depends on the combo and with a charger I would say for sure. Hi tech did a swap on a 96 ws6 car that had the factory slp cat back to a mufflex and picked up 10rwhp on a bolt on car so tell me if it is worth it with a car that makes 200 more hp? Now for headers same 383 lt1 went from 1 3/4 slp shorties to hooker supercomp long tubes and picked up 22 hp and 38 lbs of torque as I had a chance to dyno it after the swap. At that point I had the 4 inch on the car and eventually went to 1 7/8s and dual 3 inch on it and got more. This is a 383 well really 392 stroker with afr 220 heads and solid roller that makes 550 rwhp n/a. So a blower car with similar numbers would gain for sure with a header swap and 4 inch exhaust. Just my person experience and not every combo will gain as much but if a bolt on lt1 can get 10rwhp I think it is a swap worth doing + the 4 inch sounds so much cleaner and throatier than a 3 inch.

Batass

IIRC, dual 3 inch flows close to the same as a single 4. But a single 4 would be easier and cheaper. Don't have to mess with an x-pipe or an h-pipe. I made my own dual 3 inch and it was a pita. Used the welded ultra-flos also. Car is loud, but open headers its downright deafening.

I think you would definitely benefit from some long tube 1 3/4. Blower motors like a well breathing exhaust.

What cam? You'll notice a difference going to a bigger exhaust, but if your cam is a bit larger than stock, it will be a HUGE difference.

lt1z350

iTrader: (2)

single 4 inch is the easiest way to do these cars and get the most out of teh exhaust. Just sold my 4 inch mufflex due to now going turbo and didnt need that for the set up. turbo and supercharger need different things for the exhaust. No going single 3 with a ultra flow or bullet. But a supercharger should be treated like a big inch motor.

Batass

Going smaller? Hoping for more velocity?

lt1z350

iTrader: (2)

why chop up a mufflex set up for long tubes when I am now going to be running a single pipe all the way back and cant use the flowmaster any more which was 200 of the expense of it. I have been told by a lot of turbo people that a straight through muffler is the way to go and no way use a flowmaster. Most of this came for 9 or 8 sec turbo mustang guys. Most of them are using 2.5 inch duals with ultra flows or bullets and when uncapped didnt pick up squat compared to the noise it made. Not like a n/a car I guess. I was told it was over kill for the car. I dont know for sure just know what I have been told. If I need to go back to 4 will build it with truck exhaust pipe that I can get cheap hear in town. Mandrel bends for 14 bucks and pipe for 6 bucks a foot. I got 350 for my mufflex. I just think when I will have to run less boost so I dont break my car in half or the bottom end of my motor 3 inch pipe will just help keep it under 650 rwhp. Too easy to make power with a good set up. 383 afrs 195s t-76 ceramic ball bearing turbo and turbo cam = a easy 650+ on 15 to 18 lbs of boost which I dont need. Well cant run on a stock rear end or my bottom end or really trans either. See my point here? Now that I have got way off this topic but not really. Use what you need to make teh power you want. If you want the most you can go for the big single or dual 3 .