The 44's are a smaller case muffler and are louder than the 40's. I have never seen anything about the 44's being for newer cars. When they first came out the ad showed a chevelle doing a burnout with them. I ran 44's and switched to magnaflows. The 44's were much louder at idle and cruise. If you want more noise than the 44's are giving you(hard to imagine) put dumps on the mufflers instead of tails.