Hi Gerry! Welcome!
I'm running stock 16s... and installed 20 on the rear... 15 on the front. ECS sells the kits, and I'm satisfied with the product.
I'm actually looking for a trade: my 20s for 23s. I think the 23s would give the rear a slightly more agressive stance, without compromising the rear components (stress, etc.).
Or... if someone wants to trade a pair of 23s for 15s... I'd be all in.
Pics, Gerry?