The roush mustangs have side exhaust with a square tip. Look at the car alittle closer, it may be a roush mustang or maybe it just has a roush exhaust kit. Its for looks. I was going to get some side pipes for my 89 and when I called to order them I was told they wouldn't be as good as the other kits(straight kits) because of the bents in the pipes, but they do look good. A guy at work had a 68 mustang and had the pipes exiting before the rear tires and it sounded mean(good), it didn't have cats and all.. it didn't have the bents mine would have required. I've never looked at a roush exhaust but I would assume they have more bents in them than the stock pipes.
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Rick
My 89lx(updated 7/20/2001)
My 97 Cobra