Yeah, I can't think of a good reason other than the smaller cooler got them to the temps they wanted to see in testing. Possibly differences in the PS pumps between the 4 and 6 cyl cars too. The smaller cooler is definitely cheaper to produce and they used it on all the 316 and 318 models according to realoem. __________________ ~Dave~ 98 328ti Morea Grun slicktop 11 128i space gray slicktop 13 JGC WK2 Deep Cherry Search | RealOEM |