Intake size matters
CENTRI ("I have no affiliation other than using their product") which makes pre-cleaners for trucks and heavy equipment has a formula for sizing the intake, my 6.5 turbo (roughly 400 cid) requires five (5") inch inside diameter snorkel.
Normally aspired or turbo "2 stroke and 4 stroke" are three (3) separate and distinct animals when it come to cubic feet of air per minute aka:cfm flow requirements. What works well for NA will more likely than not be a restriction before a turbo compressor when used on any of the 3 aforementioned motors .
Intake side of my diesel for over a decade had a Donaldson canister from factory w/K&N filter option which was an improvement over the stock filter, recently S&B Filters ("I have no affiliation other than using their product") has released a filter box and filter that is a 44+% improvement in the flow department. This intake has the ability to adapt to a snorkel very well and I'm in the process of developing same for my use.