1. Turbonetics T4. Im not sure, but Id be very willing to be that a non-hybrid T4 woudl outflow a set of T25's, and do it more efficiently at that. 2. Compression. Ity seems that kit doesnt come with replacement pistons. That means who buys this kit will be running on the same higher compression ratio that other NA cars use versus a safer lower compression ratio that it should be running (9-11:1 versus many turbo cars' 7-8.5:1).