Jimmy P

iTrader: (177)

I got the Nasty fuel tank, and to my surprise we can't use my hooker catback anymore as the fuel tank is shaped different and sits lower. bang:.. So now I have to do some type of true dual exhaust setup.
I am wondering how much exhaust flow would be needed for 900+fwhp. I know that supercharged cars love a free flowing exhaust. I currently have Kooks 1/7 - 2" headers, with the 3.5" collectors. Most true dual exaust setups I have seen use 2.5" piping. Would 2.5" be a huge restriction for me? What about 3"?
Do I have to get muffler with a certain cfm rating, to make sure that they wont be a restriction?
I know something like this should be posted in the Generation III External Engine section of the forum, but there aren't as many high hp cars there. Any advice is greatly appreciated. Thanks!

kp

iTrader: (34)

I'm not into the dual thing, this works fine for me, I only have 3" collectors so the Y is 3" into a flowmaster merge into a single 4" muffler. Not exactly quiet but not cop calling nasty either.

Jimmy P

iTrader: (177)

Thanks for the pic KP. You dont happen to have any sound clips of the car, do you?

kp

iTrader: (34)

Only videos I have are at the track so its hard to tell anything, its loud as hell at WOT, but its not too bad at idle/part throttle. I always race the car with the exhaust on it.

TS6

iTrader: (41)

I have the same tank and run a Hooker cat back with no problems. We did have to re-bend one pipe a little so the muffler sits lower but no biggie.

I had the same exact setup as KP, it was kinda loud (especially under heavy throttle) so I took out the muffler and adapted a Hooker catback. On the 4" section of pipe I installed a 4" electric cutout. Now I have the best of both worlds, aside from the added weight of the catback, which is easily removed if need be.

FWIW, I've had everything from TD's with Dynomax cheapie mufflers to bullets off the collectors and damn near anything you can think of. I have never lost power on the dyno at any point in the curve.

Jimmy P

iTrader: (177)

Do you have any pics TS6? I want to see how much lower the muffler is going to be.
We are trying to get ideas of where to mount that Manganfuel 4303 pump, and it would be very tight with a catback back there as well.

TS6

iTrader: (41)

No pics right now, sorry. Its very very similar to KP's, except when I had the magnaflow 4" muffler we "clearanced" the floor with a big hammer to tuck it higher. My magnafuel pump is mounted on a steel plate right off where the upper panhard rod support used to bolt to, so it sits between the frame and the tank. The setup I had like KP's was the most ground clearance I ever had off all the systems I've ran.

Pro Stock John

iTrader: (34)

Ground clearance is not very good with true duals and 26" tires.

Could you just custom make an exhaust with a smaller (the overall case) muffler? Like run your over the axle pipe into a 3" muffler that just runs straight back?

My old duals with supercharger:

Jimmy P

iTrader: (177)

We did think about something like that, but woudln't that be real loud with only one smaller muffler? I figure if there are two of them with a true dual setup, it wouldn't be horribly loud.

stevieturbo

With DIY X-pipe, a pair of Moroso Spiral Flows, then into a pair of Magnaflow 8x5" mufflers, all 3" tubing....


Measuring pressure just after my LHS collector, I was seeing as much as 13-14psi !!!!


When I rebuild, I'll be re-designing. New X-pipe, removing the Spiral's in favour of straight thru glasspack Magnaflow's in the middle, and the same ones as before at rear. So effectively a full TD 3" unimpeded system.

I exit at the very rear of my car, so have to travel over the axle too.

Pro Stock John

iTrader: (34)

I think shorty duals are louder than a 3" out in back.

3"/3" into a 4" merge into a 4" muffler like kp's would flow best, it will be a loud race car then.