Look at the specs for 1943 LF IX, only difference is the LF IX has .303's instead of 50cals.
Or in other words it performs identically to a clipped 1943 LF IXc, and a clipped 1944 LF IXe.
They all use the same airframe, same engine, only reason for designating it the XVI and not IX, was the engine (Merlin 266 same as Merlin 66) was manufactured in the U.S. and needed different tooling.
http://www.spitfireperformance.com/spitfire-IX.htmlHas figures for non-clipped LF IX, look for the Merlin 66 @ 18lbs ones.
Interesting is near the bottom, what a Merlin 66 based spit at 25lbs boost could do

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Unperk the XIV it's all I'll fly, it's way far more of a beast with its 2000HP+ Griffon motor.Dace - You do realise the XVI is the same as an LF IX (see above)? And not some wierd late war Griffon engined spit.