By the way I wouldnt be worried about turbo lag with the GT's or K04s.

The best thing you could do is go to the dealer, ask questions, and drive the damn thing! Theres very little lag stock...

 

what i think you could do for a reliable motor is get an rs4 engine block from the avant that was only in europe. those cars are pushin 450 hp stock. take that motor and build it with pistons, connecting rods. then use your s4 heads as the two make a perfect performance as low end and high end meet. on the heads you should port and polish, replace the cams and possibly some things. thats good for like 60-65 hp gains as what im told and the motor comes with the ko4's. ive been told that the motors are around 6,000 and that is for the the complete drive train and all accesories. that should be good enough and you can add turbos later and the engine will take the abuse very well. you should see about garrets gt35r turbos as they are the same kind only a little bigger. you would need a custom setup but it would produce the numbers you want. you should also upgrade the clutch as well for all of the stress. that is probrably very expensive in the uper range of 25,000$ but it would be a killer car. that is what would porduce your numbers reliably.

 

The s4 will be my daily driver, I would like to get 500 whp out of it preferably onpump gas, so i'm thinking I would have to go single turbo. I would hope one of those single turbo kits coming out would only cost a few thousand causearound 15k for a single turbo kit is redicoulous, that would be a complete rip off, it would be muchcheaper to have your single turbo kit fabricated by a capable fabricator.

 

right now the gt kits are for both turbos. still more in development and single turbo kits will take even longer.
that will be one heck of a DD!!

 

I dont know if its been said but have it looked at by a independent dealer before you buy toolook for any body damage, frame, engine ect...

parts wise dv, tbb, timming belt water pump better to do sooner then later 1k job alone