I think 40 hp from the kit is a bit high. Maybe mid 20's.
I put on the Trail Jammer and a cat back exhaust when stock and it really did bring some life to my car rig. Lost some of the umph when I lifted and put on 35's but I'm still glad I have it on. I spent over $500 for eveything though (kit and exhaust) - can't recall exactly how much.
And mine is a daily driver too.