I was wondering if anyone knew if a 3" downpipe like the Buschurs or UR's will clear an aftermarket lower subframe chassis bar like ones made by Cusco and other companies?

Are there issues with ground clearance goin g over bumps?

 

Most aftermarket lower braces have a bend to clear the downpipe, or spacers to bump them down a bit below it. I have the RMR brace, along with the Buschur 3" downpipe, and have no clearance problems. Ground clearance isn't really a factor, as it is less than 1" lower, but still higher than a lot of suspension components.

 

I just installed the RMR downpipe and lower crossbrace - no fitment issues. Regarding the lowering of the Evo, don't go more than 1" - more for suspension compression than for scraping your downpipe...