Possible backfires
 

Since my tune and ambient temperatures rising I have had 3 (what appear to be) backfires. When it happens it feels like I ran over something and I can feel it in the middle of the car. It's pretty loud but not race car loud. I can hear it over my music at least.

Has anyone else had backfires?

It's happened when pulling away from a red light and shifting from 2nd to 3rd. Is this causing damage to the car?