I don't mate, have owned and modded Scoobs for the last 8 years so have learned quite a bit from trial and error!
VF24, 28 or 35 remain decent all rounders and price for bang for buck, but so do 16g's (which often make as much if not more), hence my statement.

I've seen cars on dynos with 35's, and 34's and the 34 rarely makes such a noticeable difference that it makes me look at the graph and think wow that's worth £150 more than a vf35.

The 20g in question was what I could afford at the time - cost less than a third of an SC42 (which is the only one I'd look at given the SC40 is a billet 20g anyway!), and I find it drives very nicely, don't find it particularly laggy at all compared to the vf35 it replaced, but then I'm running decent headers and up pipe.