personally i would say if you have the money and your PULLING the HEAD ANYWAYS go ahead and do it. Better safe then sorry do it once do it right and your evo can then handle anything you can throw at it. Think if it this way if you upgrade to a red of 35r you dont have to worry about throwing a rod or damanging valves etc. you want peace of mind do it hell im putting so much into my new motor im building not like im going to even be pushing it close but i want it to be way more then reiliable and i dont have to worry about being on borrowed time.

 

It's not necessary to do it. The stock block will hold more power then the bbk can dish out. On CBRD's dyno I would say 450+ you should get a built motor but I don't think you will be hitting those numbers. The highest BBK Full setup to date with upgraded IC, IM, BR stage 3, etc etc made 430 on their dyno. But if you have the money and want to put it into the car, go for a 2.3 imo. It will give you more torque and a better spool. You might want to look into a Buschur motor since you are getting their head. Very reliable motor from posts on the forums.

 

Personally, unless you're going to try to push limits with that turbo, I don't think it necessitates a bottom end build. However, if you think you want to go bigger down the road, it probably wouldn't hurt.

s for the build for the bottom end, why not have Chad build it for you? You can probably get a little more for your money than buying a Buschur block.