Gus,
Several of our customers have just gone to straight pipes! Both plain diameter type and megaphones are being run on the street. Amazingly they are not as loud as you might expect as the "180 degree" system changes the tone of the exhaust.
My one customer does admit he needs to really be careful at stoplights when the sheriff is next to him however!
There are several videos on here with SPF and straight pipes, MHNCO is one.