I cut the post o2 sensors all the way down the tube is threaded all the way down , my tune has a post cat delete, as far as the motor mount getting in the way, that’s only if the studs for the header are still in the block so you can either take them out or it’s just 5 bolts to loosen your motor mount put the header on the put the mount back in place no motor mount mods needed, if your willing to put in the work I say they are well worth the money!! If the motor mount wasn’t an issue I would give it 5 stars