I'm jealous, the driving experience of the Euro version was significantly better than the US. Mine was an 87, so it had the even extra luxury stuff, in terms of full leather dash. Those had a tendency to lift in the corners, and not wear well....dumped for 88 when they also changed the bumper trim etc....
Ug... just remembering the TRX rims too.
Beautiful car, with absent B pillars, and classic good looks. The Euro M635CSI was so much more fun to drive with more power and less weight. I believe most people converted to dual timing chains, this doesn't rob that much power, and can save an expensive rebuild. By now I'm sure you upgraded to the S50B32 chain tensioner etc.. Did you go for the Fahey crank hub?
I sold my car very shortly after a test drive in a used E34 M5. The extra power was eye-opening, and I realized I'd want one of those eventually, or something similar, a bit more practical with 4 doors.
The TRX rims were a pox on all the BMWs of the mid-80's era. Remember they were on 5 series and 7 series as well. The Euro M635s were supplied with special 3 pc BBS TRX rims which were prone to cracking and were recalled by BMW/BBS. The replacements (I still have a set of these) were single pc forged BBS rims that took the 415 mm TRX tires. The tires are still available but are outrageously expensive.
You can see a summary of my car in the other post (M6's on the Board). Frank Fahey rebuilt my Dinan stroker a few years ago. The Dinan stroker motors were supplied with a special run custom SCAT crank, which provided even more stroke than the E34 M5 cranks did. Since it was custom for the Euro M635s, it fit a single row sprocket for the cam chain, and I did not have to convert all the cam gearing to dual row. We did replace all the tensioners/chain/sprockets during the re-build, and using the updated cam chain tensioner I have had no problems since. The stroker crank really transforms this motor, providing a large amount of mid-range torque that you really can use.
And of course, I have been using the Fahey crank hub for a many years. It was the first mod I did to the motor, even before Dinan stroked it.
I consider the Euro M635 the only real performance 6 series. At 3300 lbs (with a modded motor over 320 HP) it breaks (under) the 10:1 LBs/HP criteria which I think is essential to consider it a real performance car. The US model 6 series were nice cruisers, comfortable and capable of high velocity autobahn running. But at a stoplight, forget it. And nothing matches the sound of those Euro M635 tubular headers at full song.
The E34 M5s are a nice improvement but still don't have the power/weight ratio of my stroked Euro M635.