slowness

factory MLS for sure, and 9/10 times you can reuse them

slowness

Does anyone get a tune after putting them on?? I was going to do those headers and the setup that speed engineering has but with the MF straight thru race mufflers, I already have the one

The_W

I would think you want too, because the movement of air has been drastically changed. Your air fuel ratio will be different than manifolds.

ConnorsStepside

Your on the right track. Use mls gaskets, when you go to take them all out. Warm up the truck for about 5 minutes. That will get the aluminum heads to expand but the steel wont be hot enough to expand yet. Perfect time to take them out. No it wont mess up the threads. Im about to do this same project and thats what ive researched. Make sure to use good bolts when u replace them, i got arp bolts from summit for 35. Make sure to use antisieze also on the bolts.