As for rejetting, it depends on where you are now. Rule of thumb says, you raise the jetting up one size for the gutted airbox. However, if you are currently running stock jetting and do not ride below stock jetting altitude, you should be ok. Stock jetting for Polaris is typically 2 sizes higher for a safety margin. If you want to keep that safety margin, bring your jetting up one size. I recommend that you do some tuning on the hill.
Yes, you will see a performance increase. More responsive bottom end as well as a better top end. More air = more HP.
I used a 4" PVC pipe and attached it to my airbox, then I put a 4" to 5" or 6" rubber adapter on and put a short piece of PVC in it to hold that special SLP material over the PVC and inside the adapter. It sits directly above an SLP vent. Everything is under the hood and it looks pretty slick and draws a lot of cold air in. I will try to get a few pics of it if you would like.
