Anyone have experience with them? Opinions? Looking at a complete header and cat Y pipe kit.

 

FWIW, lots of guys used to run them on my previous car. The fitment was not 100% perfect, but they worked, made good power and cost 3x less than the original design they were a knock-off of... I think the quality also got better with time.
I know it doesn't apply directly to your truck, but hey, that's the best I can do

 

I was looking at them but ended up going Stainless Works. Haven't gotten them mounted up yet tho.