I run headers, no cats and no mufflers and it is quite loud. I get mostly positive comments on it though I think the70% of folks who have negative comments keep these to themselves. The folks that matter (me and true car people) seem to like it.
Police don't seem to care...unless you're doing crazy sh*t that you shouldn't be doing. In that case I bet they'd pile-on with a noise citation.
You need a big amp if you want to hear the stereo, and 3 hour rides are really trying on your head and ears.
One side effect that I hadn't anticipated is that of noise in my own neighborhood. Though my neighbors are very cool about it, I choose to not drive the car early in the morning or come home late at night since it does absolutely wake everybody up. My neighbor across the street in Chicago told me that he and his wife are very careful to frequently adjust all the glasses in their china cabinet so they're not touching.....since when I start the Viper glasses that are close do alot of clinking. Apparently they like the sound of the car but are annoyed by the clinking.
Even 10pm is late if there are infants in your neighborhood. As a result, I pretty much enter and exit the garage during daylight only.
Joseph's cutout suggestion is the best, but there's not alot of room for 'em....you have to be pretty clever with the install. I say go for it, more "V" is always good.