I have owned a 911 Turbo with 600+ hp and a custom Turbo Hayabusa with 360+ WHP.
Both were incredibly fast!
And both were incredibly expensive and unreliable too!
paradoxical, I think you have a great set up. If you go down the 500whp road you are at double the factory HP. In my experience, that is when really expensive things start going horribly wrong. If its a daily driver I wouldn't do it. If its just a toy, go for it (and have lots of $$ standing by...)
If you do it though, please keep us updated! I can only imagine having my X1 as quick as yours, much less even faster!
