QUOTE(pete000 @ May 10 2020, 05:44 PM)
How much different are the Factory GT headers vs the stock six exchangers?
Very different, they are donor headers borrowed from the 906. Shorter primaries, Long transitional secondaries (via megaphones).
Seems the Zuffenhausen tuners deemed these "Correct" for the duties of a very high compression , big cammed, twin plug, 46 ida webers, 220bhp, 2L , running mostly W-O-T for race circuit; totally too wild for daily street use. 916's on the other hand did use heater boxes, which also included a tap-in-duct (and flex tubing) for heating the aneroid (spl ¿) sensor on the mfi pump. Most m471's (as you know) ran with standard (long primary tube) 9146 HB's.