QUOTE(TimT @ Feb 8 2006, 03:53 PM)
A & S are the same sized caliper, S is aluminum, A is steel (iron), the aluminum calipers flex under heavy braking, also the A & S have 3.5" mounting bolt spacing. These have a larger pad than the M
M calipers have a smaller pad than the A & S, are iron bodied, and have 3.00" mounting bolt spacing.
Any of those calipers will work fine, S calipers command a premium
I have a comlplete 911 front end M calipers with vented discs ( this was from a 911 T with S package)
couldnt have summed it up better meself...
i find that M calipers with an agressive pad are more than adequate to make my car stand on the nose.......
S calipers are $$$$$$$$$$$$$$$
An m caliper front end is anywhere from 200- 500
an A caliper front end is 500-800
Add a couple hundred to the above for S calipers....