I currently own a 1991 190e 2.6 and am wondering if there are any performance products available that would result in a 10 to 15 percent more power and not affect driveability. Also, I would like to know if there are any performance ecu chips available for this particular model.

One thing that can "wake up" a 190 2.6 is changing the gear ratio. I think the US cars have a 3.27 in them. If I remember in the (TDM technical data manual) some euro cars had 3.42,3.69 gear ratios. I think the 3.42 was available for the evo2 190. Of course although your car will accelerate faster, you will lose some top end speed and mileage will drop. Also, if you change just the R&P gear (as opposed to finding a complete assembled jug) you will need the appropriate "toothed wheel" that is mounted on the pinion shaft that sends the signal to the rear ABS sensor. And don't forget about the speedo,if you don't change the drive it will be inaccurate.

I have a 3.92 gear ratio "locked" differential in my 16-valve racecar, and my ABS still functions properly If I turn it on.