[quote=HammerZ71;2556632]Actually the whole thing about backpressure and losing torque (it's low end torque that's "lost" not HP BTW) is very misunderstood. Backpressure is inefficiency, plain & simple. It's actually the gases backing up into the engine at the manifold because there is a restriction that doesn't allow the gases to escape fast enough. But the pressure it builds forces the engine to work harder to expel them, so the harder working engine at low rpms is felt as greater torque.
The better the exhausts flows, the more HP AND Torque is gained. The only problem here is that the HP & Torque curves move UP in the RPM band, so even though you have an INCREASE in torque, looking at the curve at a dyno you have less of it down low. Not so good for a heavy truck, especially a hauler or tow vehicle. Of course there are ways to have your cake and eat it too, but they are costly. Re-gearing to taller (numerically higher) gears will bring the low speed RPMs up more into that higher power band sooner and a cam specifically ground for low end performance will do it.
In stock form, you want a little bit of backpressure for that low end (it's the reason why my stock cats went back on two weeks after I installed my long tube headers).

Sorry to bring up an old thread, but hammer which long tube headers did u go with?