If you get one of the kits with a compensator, yes. And in that respect, they generally come with the longer inner barrel.

No, a longer inner barrel is not required, unless you're getting one of the Shooters Design 6" limited frames.

Sir Illusion, when I change to metal slide? does recoil spring upgrade necessary?

Not NECESSARY, but it's recommended, otherwise cycle time will be much slower.

Sir, I'm having problem taking down all the back parts (hammer, safety, etc) from my original marui frame. I dont see any bolts to unscrew or anything so I dont know where to start. Do you have manuals for diassembling these parts? Thanks

Not in a digital format, no.

Try this, it may help:

http://www.redwolfairsoft.com/redwol...l?reviewID=168

http://www.arniesairsoft.co.uk/forum...=post&id=34184

Arnies is down right now, but if it ever gets back up it should be the most comprehensive guide for Hi-Capa...