Yes, like Paul posted, research more. Essentially what you want is a gearing set up that when you hit redline and shift to the next gear, you are sitting at the right RPMs that your engine will be making power instantly. you're "powerband" on your car is the rev range between where you make max torque and max hp. say for instance, your car makes peak torque at 4K rpms and you make peak hp at 7K rpms (just random numbers here). you want to be able to rev out to 7K and when you shift, you want to be geared so your next gear puts you slightly above 4K. sometimes, revving over that peak hp rpm is benificial as well. depending on where your engine is going to peak out hp and tq is the determining factor in how to select gearing. of course, you need to factor in if the car is going to be revving to redline every time you drive or if you need streetability as well. i know there are engine design programs out there for the home user. lets you enter your setup and see what the engine will do performance wise. i've never used one, i don't know how good they are, i don't know if you can factor in transmissions as well, but if you can do all that and the programs are good, you could possibly use one of those to help determine what you are going to do. Also find a few good shops in your area that have this type of experience and see what they say as well. performance engine builders have this type of experience, so find a few in your area with time to kill discussing your setup and get their advice. If the boost on your turbo is adjustable, you'll be able to fine tune it all so you can get the most out of your gearing, engine, and the turbo for whatever driving sitations you encounter.