I am about to sell my k04 mk6 to get into a 135i myself....the only "downgrade" is the interior...the mk6 interior is hands down better, but thats not why you buy a 135 haha
even though it is fast for a fwd hatch, I got tired of dumping a ridiculous amount of money into the GTI trying to make it something it wasn't(i missed rwd fun)
since everyone is leaving hatch pictures...