quote:don't you think that having ones as large as in the photo weakens the bottom of the upright too much?
FWIW, the holes in the bottom of the inner wheel house horse shoe are only 3/8". I don't feel they weaken the bottom of the area because the steel there is very healthy on my car, and I believe most of the strength in the structure comes from the edges and corner/bend in the channel. The hole in the middle of the 'field' does little to reduce the strength. Similar to lightening holes being drilled in race car chassis' which don't compromise the integrity of the structure. Likewise with holes for plumbing and electrical drilled through the 2x4's used to frame your house - no adverse structural impact if they're not on the edge of the 2x4.
Also note in the first picture the VERY LARGE hole above the small hole I drilled. This large hole is original from the factory and doesn't compromise the integrity of that structure.
One last thought. I've inspected several Panteras that had only the small factory drain holes that were so clogged with dirt, gravel, and crud that the surrounding steel was completely rotten - one car I could push my bare finger through the steel. Now THAT weakens the bottom of the horse shoe (upright) much more so than an adequate drain hole!
YMMV!