Re: gt 42
The R means it's a ball bearing turbo versus a journal bearing. The 4202 has a bit larger compressor side wheel than the 4294.
I believe most are a T4 foot print, you don't want the T6 one.
The 94 may spool up a bit quicker and maybe be a bit better on the bottom end for daily driving, the 02 will give you more top end at the track.
The mounting kits and hardware are a custom fab job for the most part unless you do it yourself.
some bolt on stuff from Bean & BTS
Some used and some home made stuff
463hp/991tq 10/01/05 mustang dyno 10k rollers
458hp/923tq 04/14/07 dynojet dyno
490hp/1025tq 03/08/08 mustang dyno 10k rollers
03/08/08 1st runs ever, 13.5 & 13.264 @ 100.65mph screwing up both launches, 7600#'s, #2 only