Hi Kevin - interesting machine you have there. I have never heard of a Martyni 23 before, and judging by the chassis pictures on the website it is no relation to the Noble/Auriga/Mamba replica. I have got a 1.5 Ti in my Nova kit car (which actually uses the Noble 23 suspension wishbones and rear uprights, as I wasn't happy with the VW Beetle underpinnings). My engine is bone stock, but I have changed the air filter box for a pair of K&Ns. The leaflet that came with the filters suggested upping the air corrector jet, as Mark says, but I haven't done that on my engine, nor have I fitted ram pipes. I think it runs OK, although there may be a slight flat spot - its difficult to tell. I left all of the breather hoses in place - the two 10mm pipes that went to the carburettor elbow castings I have attached to the rear of each filter (there is a very expensive optional extra K&N part that does this, but I just used ty-wraps), and left all of the smallbore scavange pipes in place. With the K&Ns sucking in air from all around their perimeter, the 10mm pipes are essentially just acting as vents - there is no manifold depression to scavange the fumes from the crankcase. This just leaves the smallbore pipework, which connects to the inlet manifolds below the carbs.
Eventually I will get around to moulding some airboxes for the filters, at that point I will integrate the stub pipes for the crankcase ventilation and the large bore squeegy pipe from the upper body intakes, but I won't be doing any of that until my new engine is in place.
I guess you will be running without the brake servo, I found that the hex-head blanking plugs in the carburettor elbows are interchangeable with the servo take-off stub in the RH inlet manifold. Swapping them over makes for a neater engine bay, and no vacuum leaks