ummmm, you just cannot "throw on a set of 4V heads" on a 2V engine "cheaply", thats just incorrect info:nono:
Not to hijack the thread here but, You can piece a complete 4 valve conversion for under or around $1000. AND if you Know what parts you need you can do it cheeper via junk yard. The hole "MODULAR" thing... almost everything is interchangeable on those motors you just have to know what parts interchange correctly. If your going to BUILD a motor for nitrous and change rods and pistons....spending and extra $1000 for an extra 40hp isn't that expensive and what I CONSIDER A "CHEEP SWAP" and opens the door for future plans ie supercharger, turbo setup and works 10x better with 4v heads.. I know i'm coming off looking like a no-at-all, and I'm not trying to be rude to you! I was just giving some food for thought, for someone looking to upgrade.