This is our baseline starting point: 339 WHP and 262 lb-ft of peak torque to the wheels. This car was already equipped with a Corsa cat-back exhaust, and an AFE intake. It looks like the V8 wants to have a fatter midrange, but that factory dip from 4000-6500 RPM (a rather important RPM range in street driving and road racing) kills about 10-12 would-be lb-ft of potential torque fun. In researching other dyno graphs with other aftermarket tunes, it was apparent that pretty much all of them weren’t able to straighten that midrange torque curve out. We will see how the Epic tune fairs.
Here’s a look at our baseline exhaust setup, which includes a stock exhaust with a Corsa cat-back. The car already sounds wicked this way.
This is the section we will be changing out, which includes the factory X-pipe, cats, and a pair of resonators.
In its development of its Racing X-pipe, BimmerWorld didn’t just call Magnaflow to have them send out an X-pipe and weld some piping to it. The first iteration used an X-pipe with a larger internal diameter (left). In its quest for more midrange torque, BW tried an X-pipe with a smaller internal diameter, where they found a few more lb-ft of torque with this second iteration (right).