those manifolds will support more power then you will probably make, on one of the stickys on ls1tech it mentions a truck manifold build making over 1000 hp.

 

Actually truck manifolds have gone 7's in the 1/4. Same car switched to headers and picked up NOTHING (ET or MPH wise)

 

I ran decent with my truck, twins using stock manifolds, 9.5@143mph, so ya, they will support a lot.
I just swapped to something else, we'll see if any power and 1/4 mile times improve.
Twin Turbo Truck - farmtruc goes 9.6 @ 140mph - YouTube

 

exactly. No need for headers IMO, 200mph is fast

 

What is the name of the stuff at home depot?

 

It was made by owens corning, I bought some for my snowmobile pipe about 2 years ago. I just tried looking it up on the website, but I couldn't find anything. It was the woven fiberglass pipe wrap, just a little bit thinner then the dei stuff.