I had the same shock and a +4 swinger , It was great , you do have to drill out the lower holes on your 400 shock to I think 12mm so the mounting pin will fit .
The 400 has complete adjustability , preload , dampening and rebound . Plus it can be revalved and sprung to your liking .
I have an LTR450 rear shock on my blaster with a +3 swingarm and its great! Handles bumps great and feels like I'm landing on a cloud when I jump the blaster
I didn't realize it was that easy to switch it over either... Damn I really do learn something new on here e everyday!!! I gotta start supporting this site.
It's hard to find a 12mm drill bit so I used a 15/32 bit on mine giving me a real snug fit. You may have to work on it a little by running the drill bit in and out the hole a couple of time to ream it a little but it will work.
So the 400ex shock is rebuild-able? Other than drilling out the mounting brackets, is it a plug-and-play type application or do you have to cut any part of the rear plastic for the reservoir to fit properly?
You need to drill out the bottom mount on the shock and use the Ken O'Conner upper mounting kit. I don't think it will hit the air box. It didn't on mine.