IMO, the Stillen LT's are better, but require relocating the cats and a bit more work in that department to remain emissions legal. Although, I have recently learned that both require welding, and since you are planning new cats anyways, I'd say go Stillen! You'll be mating it with a great exhaust and good intake, so you'll probably feel a good bit of power. With all you're doing, I would really consider Uprev tuning to bring out the best of it all!