Originally Posted by stashtrey
Just did some heavy backroad driving along with my brother in his e39 M5. After some extended high rpm/wot runs it felt like my car lost considerable power.
335xi with JB4 G5 map 5 35% e85 and DCI's.
FWIW I got him a couple times from a dead stop....he had a hard time hooking up but I was ahead and I am impressed I was able to hang and even get in front of him.
Signs/symptoms are exactly what you described - it just looses its punch. Add some downpipes and a FMIC and that M5 will never even see you.