two questions for you guys. Do the 98s have torque management and also do they make a longtube header for these motors?

 

Yes they do have TM. Not sure on the long tubes though, but I'd bet someone makes them.

 

You can use hooker comps or super comps from the 95 and older tbi trucks but you will need to weld on egr and o2 bungs.

Here is a link of where the super comps were used:
http://www.pacificp.com/forum/viewtopic.php?t=2430

Part numbers on summitracing:
Comps:
HOK-2462HKR - Black
HOK-2462-1HKR - Ceramic

Super Comps:
HOK-2806HKR - Black
HOK-2806-1HKR - Ceramic

 

i drive a 98 2wd sierra... ive always had true 2.5" duals and ordered some Doug Thorley Tri-Y headers last summer from summit racing... i love them. direct bolt on for my truck!