I had a turbo XP with about 400 h.p. I still have the C-4 that I was using for a very short time(200 km.). With a Dominator torque convertor and carbon fibre clutches,etc and a new flexplate and good C-4 shifter, it cost me about $2400(manual shift). These boxes are very strong when done properly(used in 10 second cars). A stocker might struggle, depending on boost. Get some quotes and find out what the different workshops do to the box. If you're interested in mine, you could send me a message if you want....Shane.