customers pockets lol but seriously the blue plug-ins (R33 and S15 $699 retail) have had bit of a resurgence lately and are so easy to fitand tune a customer can drive out for just over a grand and mod dependant im happy to use them up to 260-280rwkw.... never had a failure or an hurt engine, in fact i can match a PFC KW for KW with the humble blue up to 260-280rwkw on a R33, s13 or S15 .
The craziest thing ive had to do with blue was a full budget built NA s13 SR20 (std 120000km engine) with 740cc nismos, Z32, TD06-17c and 17psi (stupid ebay gate) and the thing was quite an animal.... made me nervous as hell but the customer did all the work and accepted all responsibility for potential disaster... the thing actually sung like a champion and idled like a stocky even with injectors 3times bigger than std which as you know is supposedly no-go with the blue..
i definately prefer the ultimate but the blue is way underated... especially for its $$$$