a 42r is wayyy too big, especially if its a 4202
the smallest turbine side you can get is a t4 flanged .86ar iirc. given the enthalpy loss through the exhaust piping (even with ceramic coating and heat wrap) itd be way to laggy



thats roughly what a stock motor looks like mapped out on a gt4294r

you need to be down in the gt35-gt37 range to make efficient and streetable power