You mean these?
Honestly, I do not know what they do for me as far as performance goes as a result of hp increase numbers. They were not part of the package, I added them in order to let the engine breath easier. More air in, more air out, with the proper fuel mixture and you are a happy camper.
I do not believe all the HP increases promised by aftermarket manufacturers with regard to their bolt on crap. Common sense and prior drag racing experience led me to Borla.
Black Lingenfelter Lux