What crank/ring are you running?
I've heard that a MRP S3 guide can work with rings smaller than 32t if the crank spider doesn't get in the way. Looking a picture, it seems as if the mounting slot is quite a bit lower than a number of other brands.
edit: This may have been what I was thinking of -
azpoolguy from MTBR wrote:
With the XX1 crank I was able to get the chain guide lower then with my old XT cranks. If you run a spiderless crank you should be able to run a 30 tooth ring and possibly the 28. I was able to bottom the chain guide out agains the top of the chain and there is still about an 3/16" of space in the aluminum mounting arm that the guide could slide down father.