Here's some data for your exhaust + chip setup: I went to the Renntech site and looked at the SLK320 mod packages and the torque gains for their Chip + airbox is 14 lb-ft. For Chip + airbox + catback exhaust the torque gain is 24 lb-ft.
I think it's safe to say that after you get your new Eisenhaus, you'll be at 250 lb-ft of torque (conservative estimate). Not bad at all!