Bingo, to pick up that extra 200 hp takes some serious research.

Ever go to the track and look at the Pro Stock truck motors with their super tiny header tubes? If you asked on this forum what size of header tubes you needed for 900 hp people would tell you something like 2 1/4 or maybe bigger. If you asked on here how big of a cam it takes to make 800 hp people will tell you something huge. Heck, people on here recommend the Comp .650 grind for bracket motors sometimes and have you looked at the specs on it? There are pleny of guys making 800+ hp with cams that are 20 degrees smaller than that cam.

Moral of the story is that there is a lot of different combinations that can be put together to build a 600 hp motor. Almost any random collection of parts can be used at that point. At 800 hp some of those combinations just aren't going to get it done. At 900 hp you'll need to be pretty darn sharp on which parts are working together and which ones aren't.