So, this morning I cleaned off the crap from the rain, lined up the template & centre punched the holes for the cutouts. Then drilled pilot holes for them all.
https://photos.app.goo.gl/8bgnbqEBoGPCv9x5A
Then this afternoon, I put a block of wood under the bonnet & a big sheet of cardboard to keep crap out of the engine. Then I drilled the holes with the battery drill & smallest holesaw. Well 7 of them, then the battery ran out, so I got out the old Sher power drill & did the rest. This thing is older than I am, (it was my father's), & the only replacement it has had is the lead, because the rubber insulation perished! I remembered from installing the AEV snorkel that letting the hole saw get too hot killed it, so I used a little water to keep it cool as I went. It also stopped the filings going everywhere as easily.
https://photos.app.goo.gl/jBpX69sPrM72toZ77
https://photos.app.goo.gl/Mz4vSsVnpZzfGUVB9
So tomorrow, I'll cut the rest out with the angle grinder & start fitting the louver. I also did it with a coat of Dupli-Color Bed Liner, for a matt black textured finish, & did the door hinges at the same time. I puled them all off the doors as they were suffering from electrolytic corrosion & the paint was blistering. Sanded them all right back to bare alloy, then primed them a week or so ago, then did both sides with Bed Liner today. That should sufficiently insulate them & prevent it from reoccurring.