Sounds like a lot of work for some wires.

Yeah @simon717, hot is the spec for a reason. The cold clearance is just a guess, you want it right when the engine's actually running.

Wait, you were using a 4-inch on a tank job? That's wild, man. I can't even picture trying to prep a big curve with something that small. No wonder the 5-inch felt like a miracle, you were basically polishing it with a toy before.