There are several elements that need to be addressed correctly here. One of them being you have to make sure the engine will consume the air just aswell as forcing it in with massive turbo's. If this isn't done properly with a correctly spec'ed engine you will be in the wonderful world of compressor surge which is a b!tch and the last thing you need. In essenence it's not just the wonderful bolt-on powder coated aftermarket inlet manifolds and fancy exhaust manifolds that will play the main role in achieving this. The actual engine spec and cylinder head is where you need to look at first and then look at whats the best way of putting the air in and out of the engine with inlets and exhaust manifolds etc. It will leave you out of pocket as you would of spent a shed load on a big turbo and perhaps custom exhaust manifold and ext wastegate depending on the spec of the turbo + the cost of doing what you should of done correctly in the first place again.

What sort of power are you looking to achieve? You don't nessesarly need to go maaaassive turbo to get good peak power and an engine that revs late. My old zetec turbo rev'ed upto 8500 rpm however on that setup I never went about 8200rpm for safety. My new engine on the other hand...... Lastly why do you want to rev to 8500rpm?

Thanks - Sunny.