Compared to the JB4?
While I do say you get a lot of bang for your buck with the JB we aren't getting anywhere near the gains they claim on their website. From two dynos I've seen it's about 20-30whp and 50-60wtq and these were cars running catless downpipes.
Hartge's numbers appear to be at the crank so not sure how it stacks up with the JB4 since numbers are measured at the wheels.
Current - 2013 N55 535xi Msport SAT
Retired - 2009 N54 335i Msport 6MT
Retired - 2000 M52TU 323i ASA Supercharged 5MT
More photos of my car here
Last edited by Alan L.; 10-20-2012 at 12:03 AM.