Monster spec! You'll have to keep it stock looking and take it out on the road to embarrass some supercars!
I think these guys do all the big hp box work over in Germany, some of the 8 second lot reference them; https://www.facebook.com/doc.drehmoment.official 5/6th gear supports and billet shafts etc seem to crop up now and again and on the German forums.
Have you got or are getting a harmonic damper too?