Looks like the awesome Michelin PSS is going to have a replacement and the launch sizes include fitment for both the Boss 302 and GT350. I ran the PSS on my Boss and now on my GT350 and they are a fantastic all around tire but could use a bit more grip for track work. The initial word is they will be stickier on track so that's good news. Read about them at the link below.
http://www.tyrereviews.co.uk/Article/Michelin-Pilot-Sport-4-S-Press-Release.htm
19" PS4S Launch Sizes
225/35 ZR19 88 (Y) XL
225/40 ZR19 93 (Y) XL
225/45 ZR19 96 (Y) XL
235/35 ZR19 91 (Y) XL
235/40 ZR19 96 (Y) XL
245/30 ZR19 89 (Y) XL
245/35 ZR19 93 (Y) XL
255/30 ZR19 91 (Y) XL
255/35 ZR19 96 (Y) XL
265/30 ZR19 93 (Y) XL
265/35 ZR19 98 (Y) XL
265/45 ZR19 105 (Y) XL
275/30 ZR19 96 (Y) XL
275/35 ZR19 100 (Y) XL
285/35 ZR19 103 (Y) XL
295/30 ZR19 100 (Y) XL
295/40 ZR19 108 (Y) XL
305/30 ZR19 102 (Y) XL
325/30 ZR19 105 (Y) XL
http://www.tyrereviews.co.uk/Article/Michelin-Pilot-Sport-4-S-Press-Release.htm
19" PS4S Launch Sizes
225/35 ZR19 88 (Y) XL
225/40 ZR19 93 (Y) XL
225/45 ZR19 96 (Y) XL
235/35 ZR19 91 (Y) XL
235/40 ZR19 96 (Y) XL
245/30 ZR19 89 (Y) XL
245/35 ZR19 93 (Y) XL
255/30 ZR19 91 (Y) XL
255/35 ZR19 96 (Y) XL
265/30 ZR19 93 (Y) XL
265/35 ZR19 98 (Y) XL
265/45 ZR19 105 (Y) XL
275/30 ZR19 96 (Y) XL
275/35 ZR19 100 (Y) XL
285/35 ZR19 103 (Y) XL
295/30 ZR19 100 (Y) XL
295/40 ZR19 108 (Y) XL
305/30 ZR19 102 (Y) XL
325/30 ZR19 105 (Y) XL