JDaniel

Keep in mind that I'm talking about a 1987 911 Carrera with 55,000 miles. Last summer the oil consumption was about 600-700 mi/qt. Car smoked a little on some startups and let out a bit of smoke upon hard acceleration from 1st to 2nd (between 5000-6000 rpms).
This summer I replaced cat. w/ a bypass pipe, and within a month began to notice more and more smoke (these two may not be related). Exhaust began to smell a bit rich. Oil consumption dropped to less than 400 mi/qt. There is a small oil leak onto the heat exchanger (passenger side) that doesn't get to the ground (just enough to give off a nice burining oil smell).
When warmed up the car will not smoke while idling, but as soon as you start off from a stop a nice cloud of smoke pops out. Not any smoke noticable while driving, but sometimes a bit upon deceleration.
There's no audible valve noise, and mechanic turned up nothing when he checked for valve guide wear 3k miles ago while performing a valve adjustment (although I'm not too sure about his ability).
Motor keeps fouling plug on Cyl #6 (plug is black and sooty, a little wet, but not dripping). The remaining 2 plugs on that bank look slightly used, but the 3 on the other side are perfect. Car runs fine after replacing plug (until it fouls again). New magnecor ignition wires approx. 3k miles ago.

So what does this sound like? The dreaded valve guide wear, broken head stud, piston/ring/cyl problem... other?

Just trying to diagnose the problem before I begin worrying about how to pay for the "Fix".

Thanks,
Dan Tolley
1987 911 (ole' smokey)