I just ordered my 335i coupe 6mt sport, I expect to get it in 4-6 weeks. I just read some posts about JB2 some questions:

1. Is this thing for real!!!???? 0-60 is sub 4 seconds??
2. Where do I get one?
3. How do I install it?
4. Am I going to quit my job and move to the midwest to race this car?

More like low 4's -- 4.4ish. Almost as fast as a C6 Corvette coupe.

http://www.e90post.com/forums/showthread.php?t=105395

Thanks Corky71. I am leasing the vehicle and I can't afford for the warranty to become void. What are some precautions I should take?

I would get the SSTT, it is easier to install than the JB2 and if you have to take your car in for service it can be uninstalled in a matter of seconds so this way the dealership wont find out what you did. Or if you really want to playit safe you can get the Dinan, It is really expensive, $2000, but they match BMW's factory warranty if anything goes wrong

Main thin with the warranty is to just remove your JB2 and put all vacuum lines back to stock whenever you need to take it into the Dealership to get anything done that would require them to open the hood. That way you will be ok.

To get under 4 seconds, you'd need to do lots of mods (search Terry Burger's car), which couldn't be reversed for a quick service visit. The JB2 alone, with lighter rims and stickier non-rft rubber will get you mid 4's that can be quickly put into warranty safe mode for a service visit.