Thanks for the replies Tom.
The tolerances must be insane if the engine needs a rebuild every 100 hours, but then I would guess 100 hours would be about a season's worth of racing on the engine?
I've come across some videos/threads with a supercharged S54 E85/86 M. What I can't remember is what changes were required to the engines internals? From what little I understand, BMW made sure the S54 was built using "high quality" parts for the engines internals, which means if you're using pretty low boost or aiming to just go past 400bhp and keep it less than 450bhp, you won't need to alter too much?
One big problem I faced with my Impreza P1, like so many classic shape Impreza's is the fact the 5 speed gearbox was very prone to blowing up if you took things past 350lbt. The only solution was to go with a 6 speed box, but you then had to swap a lot of the drivetrain/LSD's , which for the P1 was something you didn't want to do, as Prodrive totally changed all of this when developing the P1. They went from electronic to mechanical LSD's etc (not that it is, all that interesting for people on here to find out about). With all this in mind, how much power can the standard drive train take on the E85 M's?
My final annoying question for now is regarding the breaks. I was always told that the first thing you should upgrade on a car, before adding power, is the breaking. With my P1, I was able to get myself 6 pot Alcon calipers , that went over a 330mm 2 parts disc/hub setup from Godspeed Brakes. I then was advised to use EBC Blue'Stuff pads, which required a bit of heat in them before they would work at their full potential. They were totally amazing, as no matter how hard or much braking I was doing, they never once faded on me and I think I even managed to boil the brake fluid when me and a member from my local car club shared my car on a track day.
Cheers,
Felix