Well we never assume anything without thourghly testing it. I don't know what exhaust you were testing with and if it had an EC/TUV muffler, what the mapping was, if it was in closed or open loop, etc. The stock mapping on the Euro model required a lot of fuel to be removed to work properly, even with the stock exhaust. If the exhaust being tested was reasonably restrictive, there would be no advantage to increasing air intake by removing the snorkel.
The 300 is very different than the 250 and will no doubt respond differently as well to modifications; especially mapping. With a properly designed exhaust system and as importantly, properly designed mapping, there may be an advantage to removing the intake snorkel. Larger throttle bodies and intake valves, and a variety of other changes on the 300, may allow it to respond well to it being removed. But existing airbox volume may be perfectly fine without removing it. R&D will confirm this.
