I would suggest using a pneumatic jack hammer to puch new holes. (Thats my go to tool for holes in 18 gauge.) That should give you plenty of wiggle room?
LOL I just pulled the carpet back and revealed it looks like 10 holes on the driver side under the driver's seat! Lol this my 4th set of seats going in the car LOL it looks like swiss cheese already and I'm pretty sure I'm going to have to drill some more LOL last night I was reading how other people put reinforcement plates in when they put their bucket seats in? Oboy I'm in big trouble lol I say about 10 more holes and I'll be Fred Flintstone-ing it...