Originally Posted by BMWM.D.
Everyone has their own opinion on this. Personally, I go for the "simpler-is-better" philosophy. The Cobb Accessport makes installation and removal extremely easy and doesn't require splicing into the DME wiring. That's the main plus for me -- one less thing to worry about failing as well. It's a flash tune like the BMW Performance Power Kit, but much more powerful. I'd rather modify my actual DME tables than manipulate/trick them.
Power-wise it's probably a wash between the two, but the JB4 and off the shelf Cobb maps use very different tuning styles. The JB4's run leaner than I like on a FI application, but again, that's my preference. Either one is a good choice, just gotta decide what features you really like best.
I just looked up COBB, its $900 huh? No wonder people recommend JB4 lol. And I dont think my JB4 is spliced into the DME. Unless you mean plug in between it, but yea no splicing lol