I have dropped my XTZ by 50mm using
http://www.ebay.co.uk/itm/3508359837...84.m1439.l2649 (Brilliant service & next day delivery)
and dropped the forks through the yolks by (from memory) about 20mm.

Also backed off the preload at the front completely & reduced the sidestand length by 20mm.

With hindsight, 20mm wasn't enough. Ok on flat hard standing, but a bit to upright most of the time. I might wind the preload back up a bit to get the lean on the stand. Also, it's a REAL effort to get the bike onto the centre stand now!

I did all this because I collected the XT660Z brand new, 60 miles into my 1st ride between Bala & Trawnsfynyd on a single track road, went to dismount to open a cattle gate, heel caught the seat and I found myself on the brink of falling backwards down a hillside, possibly with the bike following me. Ripped my left arm tendons trying to hold the bike (3 weeks on and still painful). Hence the mods.

I'm going to splash out on a kahedo low seat as I find the standard seat the most uncomfy seat on any bike I have ever owned.

Having said all that, I love the bike. Can't wait for it to be run in. Hope this helps