I would tell a guy who's building a 500 horsepower a body that's not going to hit the track that they're wasting their money... 400 horsepower with stock heads would literally broil the the street tires off of anything... 500 horsepower and they would never get traction and when they did they would probably end up with the big enough ticket to put them in jail LOL... I think trick flow heads are great and they're best served for people putting their car on a trailer and taking it to the track...