Faster spool up, more power. The S256 is a little bigger than a 30R. Compressor and turbine wheel technology is new compared to 30 year old Garrett wheels. Disk bearing instead of ball bearing though, so rebuilds are much cheaper. Check out http://www.bullseyepower.com/racing.asp I have done 3 kits with these so far with great results!

Or you could rebuild, but my guess is that wheel may be trashed from running it without a filter. It will slowly sand blast the wheel from road grit, dust, etc.