For years, I had two T5's, one in the car, one under the workbench. Every time I blew up the one in the car, I'd swap in the one under the workbench, rebuild the one in the car, and stick it under the workbench. It was always 3rd gear, and sometimes the cluster went with it. If it was just 3rd, I could rebuild it pretty cheap, but the cluster started adding money, and when I started buying z-spec gears in a futile attempt to make them last, it get really old due to the expense. I've been accused of granny-shifting and I've never made more than about 260/300 RWHP/RWTQ in front of any of them. They just don't last.
Another area that has caused me a ridiculous amount of grief is overheating/pressurizing the gas tank. I've re-routed the lines away from heat sources, wrapped them, shielded the tank, wrapped the tailpipes, removed the tailpipes, put them back on, and nothing made a bit of difference. I've since learned that the system is WAY sensitive to being over-pumped and will aerate the gas any time it's worked hard, or even looked at, if it's a hot day. Pro-M just came out with a hanger that runs larger lines and submerges the return line to reduce this problem. I may pull my pump and add a submersion extension to see if that helps, but even stepping down from a 190lph to a 155lph made a big difference. I put an access panel in the floor of the trunk years ago for easy pump access if that gives you any idea of how goddamned many times I've had to be in there screwing with it. Beats the hell out of droppign the tank.