[pbonsalb]

If you are happy with the power of the M550, keep it. They looks great, are more comfortable and very few people actually use all of the performance of the M5. If you really needed the added performance, you would know and would not be asking. For me, it was no question — I did not even look at the M550 and have modded the M5. If you really want handling, look at smaller and lighter cars — even the M5 feels like a barge in comparison though it has very high limits if you drive it hard.