Quote Originally Posted by mossaidis View Post
Just guessing here, I would imagine that many HC cars in H1 and H2 have JDM swaps.
Likely. However the component parts are typically the same as USDM engines expect for cams and pistons. If that were the case, and assuming the cams are within STL specs, I contend the engines are compliant to the regs due to the "aftermarket source" reg and specific JDM approval is not required.

I've gotten into spirited debates with folks over this interpretation. Many contend that since the engine has "B16A" (or whatever JDM designation) stamped on it, that automatically makes it non-compliant. I disagree. The reg states something like parts must be "the exact equivalent of the original parts". However if we can obtain parts from, say, NAPA and use those, are you going to argue that the NAPA parts are not compliant because they may have different part numbers cast into, or stamped on, them? In my mind, if the parts are dimensionally and metallurgical the same between the USDM and JDM engines, and no component exceeds either OE or STL-allowed specs, then it's compliant to the STCS.

If having that "B16A" stamped on the block bothers your competition, then just grind it off.

- GA, inviting people to read his signature at the bottom...