||I bought this to test out what exactly it could do for my KWA MP7, but I never got the chance. The screw that holds the original piston in was inconceivably tight, which caused it to strip and made installation impossible. I plan on getting a new bolt carrier from KWA (if they ever decide to restock it...), so I'll be able to write a review of the actual performance.
It's longer than the original, but I have no idea how that might affect the overall perfromance of the MP7.
-May boost performance (I don't know because I can't install it!)
-May hurt performance (Still don't know!)
-May require a new bolt carrier
-The piston head just slips over the nub on the front instead of being screwed on (the original piston has a part that screws on to hold the piston head in place)
I've worked on my fair share of airsoft and non-airsoft, and the original piston was screwed to the bolt carrier tighter than anything I've ever seen. I even tried dipping it in boiling water (in case they had glued it in place), but nothing worked.
Not sure how it performs yet, but that's KWA's fault for over-tightening the living heck out of the original!
Rating: [4 of 5 Stars!]