Solid bushings are a pita on the street. I've put aluminum bushings in cars and after a few weeks the steel wears against the aluminum on the od as well as the bolt and creates slop and clunk clunk soon follows. As for welding on thick washers with a solid bushing, it can be done but still violent feeling and fine for a few passes down the track but on the street is the wrong idea. Out of all the subframes me and John checked everyone was a little different spec by a hair so just buying a turned aluminum or polymer bushing well lead to wear. I designed the bushings with John to be first pressed in then when the pin is pressed it it compresses the polyurethane slightly so no wear and being a 90 durometer is hella stiff, controls movement and as far as I know the only complains we've ever had is when people didn't follow instructions and removed the inter steel sleeve that the factory rubber was vulcanized to. I left it there for the guys up north that have rust problems. Figured they needed all the steel they could get. I have my set right now and thats all but I'm sure John (Boostx) has some sleeping in his garage.