Mine uses 1995 Magnum Truck Exhaust Manifolds. They are only 1 7/8" outlet at the flange. From there they go into a 2.5" hot side, which is WAAAAAY too big. I just didn't know any better at the time when it was built. 2" would have been more appropriate, especially being fed by the small manifolds. The smaller the crossover, the better it will spool.
From there I have a single 4" exhaust that goes all the way to the bumper with a straight through muffler.
Mine went low 10's in it's early form with home ported iron heads, a 224@.050" cam, and 3.23 gear. Really it just depends how brave you are to keep turning it up, and how good of a job you do with fuel quality and timing to enable higher boost levels.
I hope that the sequential EFI and COP ignition will help me out as well as the methanol injection. My goal has been 12 psi but, like everybody with a turbo, I'm sure that I'll want more. I don't have a rollbar and don't intend to install one, so who knows what kind of track time it will ever see.
