Typically long tube headers by nature create the most hp and tq of shorty's. Shorty's are hard to make equal length especially with a Mercedes engine. Companies have tried, but end up creating a power loss or flow differential between cylinders that can force exhaust back into one of the cylinders... when this happens it can create a lean condition on that cylinder, or alter the A/F readings that the primary O2 sensor's are seeing and cause the ecu to try and correct which by then you've over fueled the entire engine and the power loss is substantial.