About 25 years ago I installed a pair of 88mm VW forged pistons in my V7 Sport, using a set of Ambo cylinders with cast sleeves. They worked well enough, but the flat top piston lowered the dynamic compression too much with the Sport Cam , even with the increase in displacement. No power gain, the pistons need some dome. I don't remember needing any spacers, the deck height was pretty spot on. Someday, I`ll put the stock pistons back in along with nickisil plated cylinders.