Well, the 215/50/13 tires did more for cornering speed than the strut tower brace did, but the brace does its part too. I don't go around corners fast...it's more of the correct line (or racing line, if you will) so as to not lose speed. most all of my corners on my daily commute are on and off ramps.
As far as FE is concerned... the fact that I maintain or am able to increase speed on those corners keeps me from having to accelerate all over again. The FE driving techniques that I use are: Best line cornering, anticipate red lights (coast longer), slow acceleration, highway driving. And I still maintain a 50mpg 90 day average. The VX is quite a nice car