Great business had some other place fail my car. Seemed kinda sketchy since my car is well maintained. (I change my oil,spark plugs, brake fluid ect pretty often) My car did have a custom h-pipe but it was made with the stock cats. Passed with flying colors here same day as I had failed at another place. They are car guys too. I brought my ( then new to me) Bullitt mustang in a couple times. I failed one time due to having a custom tune. I had forgotten to drive 50 miles after reflashing the ECU back to stock. They knew exactly what the problem was and I passed the next day when I retested. If you've got a modded car these guy will likely know how to find the problem as to why you failed.