Hey all I have a 97 civic DX coupe with Domani front end conversion and a OBD0 B16a swap converted to OBD2 sensors. The head was switched to an OBD2 head However I had noticed more power with the OBD0 head. I had transplanted everything including valves and cams over to the OBD2. Is there a Porting difference perhaps between the two heads?? Shortly after I had swapped the motor the engine blew because my dad had wired the injectors backwards and toasted a piston. After that, we rebuilt the entire motor pretty much. We had picked a B16a2 from a friend that had an EM1. The same thing happened to him only he was running a turbo. However we took both heads in to one of my dads friends to check out and he said the OBD2 head needed only the exhaust valve guides, as for the OBD0 It needed both sets. So he said it would be cheaper to press in new guides for the OBD2 head.. He dint notice a difference in heads but again he wasn't a Honda guy. He boiled the head and ground down the valve seats so that they would seat flush, then put it back together. The main complaint as I said before is a definite loss of power. We had replaced all the rings and the bad piston. The cylinder walls fortunately weren't damaged they just had particles of aluminum on them that we honed out. The guy checked out the block as well and told us it would work fine. So we've got it together and had it together for about a year and a half but power is much less than it was before. I haven't got dyno sheets from either head but I had noticed a big difference. Some one on another forum asked me why I've switched from the OBD0 to OBD2 and I told him, and asked why had he asked? I haven't gotten a response. Recently we found one of the rod bearings had spun so there may be a deeper routed problem than a head difference causing the power drop. The car hasn't had more than 500 miles on it since the rebuild and the car hasn't been driven hard. The mechanic seems it curious that we dint have the block boiled when we had the head boiled. But my main question is the heads. Is there a difference internally besides cams, valves and springs.. between an OBD0 head and OBD2?