I got a box all made for a 12" double walled all around. is it ok to make an adapter sort to say to open the hole up 1/4" because i am not able to cut the hole any bigger. the only thing is that the sub is also too tall i need 11" of clearance and i have 7 1/4" of clearance to the vent. Is it ok to have a like 4" lift panel? i dont know if having a cylinder type thing then the box will screw anything up.