"Converting a car to dual exhaust with a single outlet downpipe is just stupid anyways...LOL if you think you get more power with a "Y" pipe and two mufflers when it is all still coming from the same SINGLE OUTLET DOWNPIPE"
I hate to tell you, chief, but you are wrong on this one! The limiting factor on any exhaust is the down pipe diameter, yes, but if the the system beyond that single down pipe has any restriction in it like a single restrictive muffler coupled with a single pipe after the cat, anything that increases the flow after the downpipe and reduces the restiction will help with power assuming that the downpipe diameter is not maximizing the flow for a given engine. On the other hand, if the car originally has a single downpipe with appropriate sized y pipe and mufflers, then switching to a larger more free flowing cat back system will have a minimal effect on the engines output, aka a GT/GTP. Conversely, taking a single downpipe of appropriate diameter or a front y pipe and running the exhaust through a single pipe of a larger enough diameter will produce power equivalent to a true dual exhaust. Physics here, no heresay! Sorry to disappoint!
