i took that ruber seal off when i did mine. its pretty pointless if you dont, you arent getting the maximum airflow if you leave it on. and yeah there pretty decent, they add pick up. might want to consider a biger throttle body too, they always help, either just a 5ltr throttle body or mace engineering do a 70mm i think. also, what everyone is saying about the bonnet not fitting ? grab a hair dryer and heat the corner of the intake, than when its warm push it in a little, with say a screw driver or something ? it does say in the instructions to do so, or to cut the corners.