RE: Welcome to Club SAITO !
Jack:
It's not just the Saito engines that benefit from the intake stack. My first experiment was on a two stroke, a Magnum 25 GP. I'm still running that engine, and it is both cleaner and more economical than it was when new. Almost any piston engine will have an amount of back spray at some point in its operating range.
So why not standard equipment? Many people don't even think about back spray, they think it's blowing back from the exhaust, they spilled some fuel, or just don't think about it at all.
The stack alone does some good, but for the greatest gain the sir filter has to be added.
Saito could include the stack at no great added production cost, but the air filter would require dealing with an outside company, or starting production on their own filters.
So, bottom line, it's cost, even though I think it would be a great marketing device, possibly an add-on accessory "Economy Kit" or something similar.
But since they are selling all they can make, why bother?
Bill.