Oh look, the Phantom Style exhaust. That explains your fitment problem. That pipe is designed for cruiser frames with more distance between the seat tube and front downtube - basically Felt Faker frames, Huffy Cranbrook, and Hyper Beach Cruiser. Basically, if the front mount can bolt to both tubes directly, you are likely going to have this issue. I know because I had this same issue with my Kent Nazz gravel bike and my Phantom exhaust.
Only way to properly solve this would be to cut an shorten the pipe. The best way to do it with this particular pipe would be to cut it at the weld joint at the red arrow, then remove material roughly along this straight section where the yellow line is, and finally have it welded back together. It will probably only take about an inch to fix your problem.
Only way to properly solve this would be to cut an shorten the pipe. The best way to do it with this particular pipe would be to cut it at the weld joint at the red arrow, then remove material roughly along this straight section where the yellow line is, and finally have it welded back together. It will probably only take about an inch to fix your problem.