Exhaust is primary. I get pulled for it all the time, even in cars with stock exhausts. It's the excuse cops use when they want to pull someone over and harass them and have no real reason.

Shits getting ridiculous. I was driving my colt the other night (1.5L 100% stock gas mileage beater) and happened to have my datalogger on me (was on my way back from tuning a car). For shits and giggles I decided to hook up the datalogger to the colt and make sure everything was good since I hadn't put a logger on it since I bought the car. I pulled into a parking lot and got out a flashlight and leaned down to plug the cable in the connector and all the sudden flashing lights roll up on me and they are asking me a million questions about what I'm doing and why, and tell me I need to go home and that they are adding me to the nightly suspicious persons list.