they all fit. the difference is in the bore size. all the TB's have the same bolt pattern/tps/map sensor. i don't think an s2k TB will work because i've never heard of anyone doing it. but i know that the H22/B series/D series TB's are all interchangeable. however, if you upgrade to a bigger TB and do not match the bore of the IM to the bore on the TB...you will probably not see a damn difference in performance.