The impellar upgrades come together as a housing and wheel. I mentioned getting a 60mm wheel, and some smarty pants came back with "I dont think the 54mm housing will fit over the 60mm wheel." Just stating the obvious, that's all

For your towing, I'd consider an HX40- most come with a 16cm housing, a 58-60mm impellar, and a 4" oulet for the exhaust. That will help a lot to keep things cool. Expect to spend around $800-1000 for a new one.

If you dont want to go with a 40, you can get a 16cm ex housing, and a HTT 60mm compressor (impellar) wheel AND HOUSING kit. Basically, the HX40 takes those sizes and adds a 4" exhaust outlet.

DP