If your going to build a ka-t get a second block ( you can get them for free especially if they don't run, and since your rebuilding it, it doesnt matter if it runs.) Turbo stuff is fairly expensive, but I would recomend a t3 b/c of the displacment of the engine. A t25 would cause you to run more boost for the same power, and you would end up having to replace it after 300hp or it will just die really quick . Also you need something to control your fuel or you waisted all of your time, so options are EMS, piggyback, or something cheap like a safc.

cheap version, part together a stock turbo system from a sr20 and have fun modifying it . good for about 225hp!

But I agree with the others and just get suspension, and if you wanna go faster.... strip it. power + wieght = speed.... I think every 10 pounds you shed= 1 hp