Headers - Shorties or Long Tube?

[Technick]

Not knowing what H.P. level the car has now (any dyno runs yet?) then 25-35 is not out of the question. With a high flow cat X-pipe, you should still be emission legal. The cats on aftermarket X or H pipe will only cost you about 5 H.P. on a 450 rwhp car compared to no cats at all! Above 500 rwhp then the cats are more of a liability. I have seen increases of over 60 h.p. with a well tuned car when changing from shorty headers to long tubes. Any supercharged or Nitrous equiped engine will respond much better than a N/A engine to long tubes. If you are cramming more air in you have got to let it out! Remember the engine is just a air pump, pump it in, pump it out! The more efffecient the pump the more H.P. The engine will only produce power to the level of its largest restriction, be that inlet or outlet.