JakeFusion

iTrader: (7)

Would the Mufflex 4" Exhaust with the Spintech single in/dual out muffler be that restrictive on a 416cid engine doing something close to 550rwhp on open headers?

There's a Trans Am here that wants to run true duals out the back or 4" mufflex. I have no mandrel bending equipment, so maybe if the 4" Spintech doesn't work, is there a Magnaflow muffler that has a single 4" in and dual 3" out? I couldn't find one if it exists.

Thanks,

slow trap

iTrader: (22)

i would think a single 4" system would flow as well as 3" duals but that is just speculation,i used to remember how to figure how much certain diameter pipes flow but i forgot.i'd say if the true duals were dumped they will make more hp but who knows. i only lost 6 rw on a single 3" catback going from 517 to 511 but the cutout is only 3" also so i may have gained alittle more if i had a 3 1/2 or 4" cutout.

snake charmer

iTrader: (118)

Just because it is a larger cube my vote would be 3" duals out the back . Though on the otherside Patrick G has a 3"y to a 4" mufflex in a a 346 that makes 507 rwhp .

JakeFusion

iTrader: (7)

My concern is that the Mufflex 4" with the Spintech doesn't flow well at all. I don't know if it does or not. But it's a crossflow muffler and they usually suck.

So even though a single 4" pipe is actually perfect in terms of backpressure and diameter size using David Vizard's calculations for this power level, if the Spintech flows like a single 2.5" pipe, for example, then it'll kill power. That's why I wanted to know if there was a replacement muffler out there? I know Hooker and Magnaflow flow really well in 3" configurations, but is there anything I'm missing for a 4"?

Oh, and dual 3" is actually good to about 800FWHP. Single 4" is good to a little over 650FWHP if it's an open pipe NA. So, you stand to make a little more torque with the 4" single or dual 2.75" vs 3" duals on anything below 575rwhp.