Intake stuff I believe is nearly all direct bolt on with no issues at all. I dont know about the exhaust, but I do know the engine in the M sits an inch or two farther back in the engine bay and so while the M is 2" longer than the G, if the engine really is farther back then the exhaust may all be the same.
Personally I like custom exhaust, it is way more fun. Do some searches on here for other exhaust posts and threads and you will find some more info on different types of parts and hopefully some active links to vids of members here with stuff like Megan exhaust to see how things sound.
Im actually about to redo mine in the next month or so again too