Shawn, what model Cobra you running and what engine and HP? Generally speaking...if you raise your engine a 1/4" your rpm's will increase somewhere between 100-200 rpms. What is your engines rev limiter set at? It's possible to raise your engine height and increase the rpm's but actually lose speed. If that happens you need to lower it back down and consider having your prop blueprinted for maximum preformance. What size manual jackplate do you have? How's your hole shot and GPS speed at WOT?