To answer your question, yes I think that 15's would be a real overkill.
FYI I run 175/60/ 13 Bridgestone R's and that works really well. A 205/50/15 with an A14 is just too much- these are light, little cars and with modern R compound tyres stick like the preverbial to a blanket...You simply don't have to go to those extremes.
I would have thought even with your engines performance 185/60/13 should do the trick nicely.