Originally Posted by flipm3
As much as many of us want to hit that 400whp NA Benchmark, I would try to focus more so on the change in power. These E9X M3s dyno stock very inconsistently throughout the world and for various reasons. When stock, there is evidence of stock E9X M3s having such a wide range of results all on the same type of dyno in similar conditions, but chances are they perform nearly identical.
I would roughly estimate that a primary cat delete, pulleys, intake, and a proper tune (Epic, Evolve, ESS, or BPM) would yield roughly 40-50+whp.
This ^ ^. Flip knows what he is talking about probably better than most here.
Here's my 2cents: 1) Because torque is lacking in the mid-range, a catless mid-pipe will do wonders in increasing torque from just off-idle and through the mid-range (where the M3 needs it) all the way to redline; 2) get a tune which increasing redline to 8,600-8,700. Start with these two things...and my guess is that you won't care about your dyno number. Your car will FEEL much faster and WILL be much faster.