Low Wheat Malt Efficiency

I'm been getting pretty low efficiencies with the two Hefe's that I brew. I'm brewing an "Imperial Dunkel" (43% Weyermann Wheat Malt) and getting about 63% and a regular hefe (60% Wheat malt) where I'm getting 60% pretty consistently. I'm brewing the Imperial Hefe today, I tried adding some 5.2 to the mash, but that didn't seem to help with anything. I've tried a finer grind, but that didn't seem to do much. Any advice on what to try next? Protein rest? Thanks a lot!

are you using malted or unmalted wheat? At any rate, one of the things I've always done w/ any wheat beers is to do a protein rest a 122degF. This helps significantly at getting at those undermodified proteins etc. This months zymurgy also noted that a step mash is pivotal w/ wheat beers... they say to get true flavor, Do an infusion mash... too much work for me

What's the OG on the imperial batch? Usually, efficiency is lower on them because you can't sparge as much.

My target is 86, but I've been getting around 70, for a 10-gal batch I do a 10.0 mash and a 8.5 sparge. I realize my mash water is pretty high, that keeps it nice and workable with all that wheat (and other grain) I could try 9.5 gal, but I wouldn't want to use any less mash water than that... Ill give a protein rest a try next time. What about some amylase enzyme during the mash?