Im pretty sure I have an exhaust leak either from the gasket or the stock manifolds. I figured it might be worth just replacing the manifolds with some headers while I'm at it as they seem fairly cheap and easy to install. What do you guys recommend? Is there any tuning needed for a header install on the 3.8L? Any brands worth looking at?

 

Go with Dorman manifolds, they've got a lifetime warranty. Headers are a waste. They burn up plug wires and have the same leaking issues you'll have with stock manifolds.

 

My 3.8 Jk is boosted so maybe not the best answer to your question but a set of obx long tube headers moved the torque lower and enhanced drivability while being top HP neutral as dyno tested. I am told ripp headers are the best but these were 3 times the price. Don't bother with shorty headers. The stock manifolds are just as good from a performance point of view. You will need a tune to see any real benefit. Good luck.
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