So far so good except for one problem. Uncertain why this would happen on a road trip using different gas, Terry Burger said it should make no difference, but had two occasions when I got the big engine light and car went into "limp"(?) mode. No problem solving it, just turned off car and restated it. Took the car to my BMW tech., he has all the test gear, and the problem appeared to be that the waste gate was staying closed too long causing an over boost situation. Did not write down the codes. Terry Burger said it may be due to a "lag fix" program induced by a heavier car. However, both incidents occurred under very low throttle angle. Regardless, I dropped the J.B. stage down from 5 to 4 and the problem has not reoccurred. However, I've not been on a road trip or put strange gas in it either. I do remain happy with the product.