We are installing the interior on the TR4.....found this info on a site which sent me to U tube. Had to do a number of holes in my carpeting to accommodate seat frames etc. Take a socket of the size you want the hole.....put it on an extension, heat it with a bernzematic torch for about 10 12 seconds and it goes through the carpet and rubber backing like butter. It also seals the carpet and backing together.....no frayed carpet threads.