Originally Posted by cliffyk

78 mm is too big for n/a on the 2V engine, and somewhat counter-intuitively won't do much for f/i when running a centrifugal blower or turbo unless you're running pretty high levels of boost. Once you start pushing air into the engine the manifold/lower plenum, and that there's only two valves per cylinder¹, become become the weak points.

That said, it's negative impact on n/a performance won't be a big deal at anything but higher rpm (5000+) WOT, and you get bragging rights when talking with people that don't know any better--which is most of them...

-------------------------------------------------
¹ - An example of how the 2V heads affect performance can be found with my "little" 400 cc (actually 385) scooter. It is EFI, has a 4V head, and puts out 24 rwHP (32 fwHP claimed. the CVT drive eats up 25%).

That's 83 fwHP/liter, from the factory.

Compare that to my bolt-on, well tuned (if I do say so myself) 4.6L 2 V '03 GT, that peaks at 262 rwHP, probably 308 at the flywheel --or a lousy 67 fwHP/liter...