hell prolly run about 1/10th faster time . You also have to remember stock wheels are also bulky and heavy.
So when you upgrade and get bigger wheels but smaller tires isnt it relativly the same circumfrence (sp) ? Most people I have seem run with 17s and then 14 stockers usually run about 1/10th slowr with the 17s on. Of course you throw the 19 bling bling Niche and that will slow you down but find some nice touring alloys or a nice race design and you wont fall in wieght as much .... let the debate begin ..but thats my $1.49