Saw a LS7 powered one at my last track day. Was incredible. Penske shocks, APR aero. Looked like a ton of fun. They can be had with V6s as a cheaper option though.
Here's a picture of it following me. I can't get the picture to embed or download unfortunately so heres a link. http://www.dropbox.com/sh/jc6cg62vmx9m6ml/AAAgJXerDbmAnQiy8vArvGJza/HPDE%202/%23313%20Miata?dl=0#f:IMG_3294.jpg