well, spent the weekend with my boxster with manual steering. results the same as reported by bayley here ...
http://986forum.com/forums/boxster-racing-forum/65308-anyone-running-manual-steering.html
the power rack was professionally converted to manual by the machine shop and, since i have no ac, i used the gsr dummy pulley. the pros - more hp. no dyno info butt or otherwise, but i was hitting the end of the main straight at our track consistently about 5 kmph faster than before. another pro is that it cleans up the engine bay nicely; with the ps, ac, and sai removed it's not so busy in there any more (just gotta get the bigger oil cooler in, delete the charcoal cannister and the associated purge piping, and perhaps replace the aos lines with something less plastic, and i am done in there). and, of course, about 20 lbs of less stuff to slow me down (or piss fluid all over my engine).
the cons? steering is tough. we run a technical track here and it is a lot more work maintaining a line. over the course of the day i adapted, but do think it slowed me down a bit (although by the end i was running as fast as before the change). i had to change my hand position to 10 and 2 to get more leverage on the steering wheel. sure can feel the track though. for street no problem once you get used to it, even in parking lots. will i keep it manual? yes, but only because my current car will see mostly street use once i get my race car built. and the race car will get the electric steering system.
another thing to report - i'd been on the rennline adjustable transmission mounts (blue - sport) all last year and did experience an increase in vibration, but that may have also been attributable to the full chinese catless exhaust, or the fact that i'd removed all the insulation around the engine at the same time. the slight increase in vibration was more than offset by the improvement in shifting. well, this spring i installed the function first 'sport' yellow engine mount insert into my still in good shape 987 motor mount and did not experience an increase in vibration. mind you, things did not seem to get any stiffer with the addition of the insert, so uncertain if it is a worthwhile add-on or not.