Although I agree with most everything that Auditech has said, I dispute the 589whp K04'ed car, the biggest numbers I have seen are well below 500whp, in fact more like 450whp, and we are talking well tuned machines, 589whp may have happened to be some freakish set of Wednesday K04's on a Wednesday motor. You can definitely run K04's on a stock motor, no need for injectors and airbox upgrade, but you can only run what is requested by the file for boost, if you deviate more thatn 2-3 psi you will get throttle cut, which will make you slow

 

Interesting. Then how much hp could I reasonably gain by just going with K04s and plumbing; versus K04s, plumbing, new fuel injectors, and maybe a GIAC reflash (assuming GIAC can do that)??

What else should be strengthened? Should I have a new head gasket installed? Replace all the vacuum lines and hoses? I'm sitting with 153k on the original motor and a stage2 clutch -- I'm not looking for 500+ hp but I'm at 318hp today (in theory) and would not mind another 50-100, but do not want to risk blowing up the motor. I want to continue running this on the street, never at the strip.

 

A 3- car , with a giac tune is reportedly 390chp, you would not need to upgrade anything, except maybe mounts, you already have a capable clutch. You almost never make enough power on K04's to blow the motor (ie snap or bend rods), the headgaskets are not prone to failure either