I have a KSC mp7...and have since swapped to the A+ hopup rubber and a Ready Fighter nozzle. The hopup rubber was necessary since the stock one is very soft and absorbs oil readily. The hopup action of the A+ rubber is very good...and no issues with feeding that's not uncommon with stock rubbers.
The nozzle wasn't necessary...but I wanted to try it out. No issues.
The ratech naps is nearly a POS IMO. It's marginal and a PITA to use. A stock KSC valve or Dynamo's valve oe the low power bolt is a better option.
I've used the mp7 more than a few times in outdoor games. It's great if you're doing c&c and want to shed some weight and clutter.
The only downside is how fast you'll find your mags empty....best to stick to semi
