You can go for a hybrid engine. You can buy a dohc h22/h23 head and throw it on your sohc f22/f23 bottum and gain about as much as a turbo in the process, and you'll be able to rev up to 7200rpms. Its VERY cost effective (about $1200-$1500 in parts). Its really new to the 'import scene', but has been proven many times over. Plus, if you want to ever turbo your car you wont have to worry about throwing a rod, and blowing up your engine so easy because i has a strong f22/f23 bottum.... If you want more info on this swap, you can read this 25+ page thread of many people that did it. http://www.honda-tech.com/zerothread?id=776837