how much horsepower increase with high flow cats?

 

It's not a matter of hp increase but the ability of the engine to breathe easier releasing just a bit more pressure. It does help "increase" output but just adding high flow CATs is only going to give you maybe 5-10 crank hp at the very most. They are still restrictive.

 

Well if you put a set of long tube headers with them you'll get 30 RWHP and maybe a little more.

Phil

 

do you have to pull the engine to put the headers on ?

 

No but it is a big job!

Phil

 

would it give me good low end torque