Before we get into the results we should first outline the lengths we've gone to make this a fair test, we have no affiliation with either design so we're not trying to sell anything, we simply wanted to know if all the hype about the 120mm aperture airbox is true.
The car in question is a 2003 E46 M3 with a standard healthy engine with the only modifications being a Mishimoto electric fan, TRS custom tuning, and the airbox itself, every other aspect of the engine is completely stock. This car was also running the factory fog light air feed directed into the mouth of the snorkel.
We conducted these tests in a back-to-back-to-back order meaning we tested the CSL snorkel for 3 runs, 120mm 'V3' for 3 runs, and then the CSL snorkel again for 3 runs all within quick succession of each other and give each design the best chance possible. We even taped up the seal to make sure there were no leaks!
We've found when testing S54s on our dyno that the more runs the car does in quick succession the hotter the oils get in the engine, gearbox, differential etc. and hence we see the car Pick up 1-2BHP per run.
Run 1: 370.1BHP 366.8NM
Run 2: 371.2 BHP 370.2NM
Run 3: 372.6BHP 368.9NM
120mm V3 snorkel
Run 1: 360.0BHP 356.7NM
Run 2: 363.7BHP 361.5NM
Run 3: 364.8BHP 363.6NM
CSL Snorkle Again (immediately after)
Run 1: 369.6BHP 363NM
Run 2: 371.3BHP 366.3NM
Run 3: 371.9BHP 367.0NM
Our test shows a clear verdict that the CSL Snorkle outperforms the 120MM V3 design on every run for both power and torque, when compared against each other there is a small but noticeable separation between the two best runs of each snorkel design.
We also found the CSL design sounds significantly louder and creates a more aggressive note, so that's the one we'd choose for sure.