I have the same dilema and I have settled on going with an 18" setup with the New Toyo R888 for trackday & Solo 1 use.
I will be using 255/35-18's which are 25.1" high for the fronts
265/35-18 25.4" rears
At least this combination will retain some of the stagger of the stock setup and will lower the tall stock gearing by a little bit.I am still checking on the availability of the tires as Toyo in Canada has never been great at supplying "funny" sizes in the performance tire line.Once I know I will start working on a wheel setup.
Failing this I will probally just run 245/40 - 18's all the way round and least I will be able to get the back around to come around!I want to run the Toyo's as they support Grassroot Motorsports big time in our region.