UPS guy just delivered my new RSR ExMag exhaust today and I can't wait 'till I put it on! Also I just installed my new Greddy header on Saturday night- my first 2 upgrades after my extensive tune-up; but when I tried to turn on my car on Sunday, it wouldn't start anymore. I checked my battery's voltage and it was good. I think it may be my starter; it doesn't even crank. It has never hesitated when being started.
I have 2 questions, any and all help is truly appreciated:
How can I test the starter?
What else could be the cause?

RSR exhaust box.jpg

RSR application.jpg

greddy header2.jpg

Greddy header.jpg