Hi i have a ultra in .177 had it regged by xtx air [darrin] what a difference it made to the gun. It cost £120+20 postage £140 on top of the new ultra.I must say i was told i will be getting 60-70 shots but only at the best 47-55.If you add a gauge+ walnut stock +mod on the end it works out more than a HW100.Darrin is a very nice bloke and very good on guns to.