Jeep exhaust Manifolds instead of headers, are these the large opening manifolds?

One other thing to note with long-tube headers is the secondary tuned length is very important... you want to keep the same pipe diameter as the header collectors as far back as possible, necking it down right after the collectors kills a good bit of torque below peak. This also applies to manifolds, you want the same pipe diameter after the outlets for at least a few feet to keep the velocity up. Bolting 2 1/2" pipes to manifolds with 2 1/8" outlets will take away torque.

This is another thing I think will pick up power for my combo, planning to run 3" pipes off the collectors at least 40" back before a crossover, if I run one at all... if I do it'll be H-pipe. Has X-pipe now and I don't like the sound. Also will likely keep it 3" all the way to the mufflers.

Sorry for rambling about my own stuff lol not trying to hijack the thread.