Personally i wouldn't bother with the induction kit, if you can get one, i had one fitted on a VW golf VR6 and it wasn't noticeable, the back box sounds like a good idea.
I'm presuming it's M111 2.3 Kompressor? If so, I'm fairly certain nobody supplies an off the shelf induction kit for your engine. You'll need to buy the associated parts, tubing, hoses, clips, filters etc and make it yourself. There's several different ways it can be set up, it depends on if you want to connect the Bypass to the inlet or have them separate. Have a search online, I'm sure there's a good few photos of various setups.
As for the back box, as already mentioned I too would avoid those cheapo eBay jobbies, they're cheap for a reason. What you could do and it's rather effective is get the centre resonator deleted and replaced with a straight pipe. You'll get a nice growl and lose c.6Kg from the car into the bargain and it won't cost much to do either.
P.s. From memory I paid fifty or sixty quid to have the resonator deleted.
Hi I think any exhaust fitting should be left to the professionals, what with rattles and maybe blowing i think it's more trouble than it's worth, that's if you can even get underneath it.
Here's a photo of a typical homemade setup, I'm not a fan of this setup but gives you an idea. I'd consider it worthwhile doing provided it assists in drawing in cooler air with less restrictions than the standard airbox which has to benefit the supercharged engine as air induction temperature is critical for performance. Heat is the enemy of any S/C.