This is something I've been thinking/making enquires about and from what I can gather so far, the T heads have: Hardened valve seats Hardened valves (exhuast definitely, not sure about intake) Stronger springs Different plugs The castings are the same and the cams are the same. With all that in mind, stock n/a and T heads should flow pretty much the same. The only real benefit would be from a strength/longevity perspective. That said, if you were to build a tough n/a engine (balanced crank, forged rods and high comp pistons, custom grind cams), a ported and shaved T head might be a good option for those same reasons.