hello welcome to the forum i have a gtt,i dont know of any cheap tunning tips!, but mine has a front mount intercooler,hks induction kit and dump valve,hks exhaust with decat pipe,a nistune board in the ecu and an upgraded fuel pump and a boast controller,with all this fitted a remap brought out 320 bhp my next step one day is to put a bigger turbo on which i,ve been told will make about 380,without going to the expence of bigger injectors etc,so really just by changing the induction and exhaust etc can make a difference good luck with what ever route you take in tunning your car,they are a great car in there own right .