My car has the mods in my sig and yesterday I had my car dynoed and I was pleased with the results 350rwhp 355rwtq. I would like to get my car up to 400 hp range come spring time and i had 2 mods in mind. 1) get a mail order tune by frost (i hear he is the best) 2) put a high ratio set of roller rockers on. So what is the highest i can i could put on for roller rockers without running into problems maybe with breaking springs or clearance. Also mind you i did not put the tb on i bought it that way i have read enough no here where i would not have done that. On a different note from the dyno my car is running rich about average AFR 12.6 so would the tune take car of this or should i be in the market for a stock tb? Thanks

P.S. Everything else on the motor is stock

 

If you truely want 50 more hp then get a cam kit, LS6 intake, and a dyno tune.

 

You'll never see 400rwhp without getting into the motor or going forced induction. Aftermarket high ratio rockers are a waste of money for a couple of reasons: they make little power on a stock engine and once you replace the stock cam they cannot be used.

If you want to improve performance without spending too much, you should look into an LS6 intake and a 3.73 or 4.10 gearset.