Well that particular datsun already had its cherry busted :)

I agree its alot of work but it does add strength if done properly to some areas that are flat flimsy steel.

eg. you can have a strip of 1.6mm thick flat stee then add
some speedholes (tapered ones like on truck cabin steps or
suregrip alloy plate) and its much harder to bend.

On further inspection the linked product has no tapered dies?

this is the stronger result of tapered or flared holes
http://espimages.biz/2386/I/525/2/images_k%20851.jpg

here is the hole punch and flare tool
http://www.motorsport-tools.com/hole- ... wage-tool-1-p-268069.html