i have a 98 gsr w aem intake, hytec headers (on the way) dc sports right now, and invidia full exhaust... i make good power and run 15.0 at track w bs 17" rims and tires.. got 15 ls mesh and awesome tires now..but i was wondering if i buy an apexi vtec controler how much would i gain and also how would i tune/tweak it myself?

 

not much. 5hp perhaps 10hp tops. As much as I LOVE the apexi controller, the problem with it was the fact that whenever you made changes using the stock ECU, the ECU will not like the timing changes and try and retard timing to adjust it back to stock. That was the main reason why its no longer used as a tuning tool for power.