I'm trying to get the power wire for my amp through the firewall but I just cant see how it can be done without drilling a new hole, the factory gromits are stuffed tight with wires.

Can it be done or will I need to make a hole?

use the factory gromits, carfull using a screwdriver or snips make the hole in the gromit abit bigger then stuff the cable through thats what i done :)

Alternatively, you can drill a new hole but you'll need to source a rubber gromet suitable for the size of the hole and the cable that needs to pass through it. You can get them in all sizes from eBay.

Goes without saying, but be careful where you drill and make sure there's enough room so the drill bit doesn't stick through something it shouldn't on the other side.

Cheers guys, to be honest I would rather drill a fresh hole rather than sticking a screwdriver near the factory wiring, it could easily get damaged so dont want to risk it. I bought a rubber gromit from a local shop which fits the wire perfectly so i'll drill a hole and get someone to spot on the other side when im doing it.