Yeah, what's new Rusty?

By the way BonzaiCelica, Back pressure is a myth for both NA and turbo, it's dyno proven that by having no bends, mufflers, cats, resonators in your exhaust your engine will yeild more horsepower than by having them.
Exhaust tuning is about the exhaust diameter being the correct size for the application as to flow enough so it wont choke the engine at peak power but small enough so that the exhaust pulses dont expand, cool down and therefore slow down. When each exhaust pulse leaves through the piping it creates a vacuum behind it causing it to do 2 beneficial things in terms of total power production,
1. the vacuum created by 1 exhaust pulse exiting helps to pull through the pulse behind it aiding in extracting gasses faster, this reduces energy loss from the piston pushing out the gas (pumping losses).
2. the vacuum also helps pull the intake charge through during the slight overlap period of the cams between the exhaust stroke finishing and the intake stroke starting, this is known as a free supercharging effect.
Adding back pressure into the system reduces the effects of points 1 and 2, and increases pumping losses.
The reason your factory exhaust is so is for a number of reasons none of which include performance.
1. Remove as much noise from the vehicle at all costs
2. Remove as much CO and NO2 emissions from the vehicle at the cost of some performance (a sizable amount)
3. Sensible routing of exhaust piping and components so they dont rub, scrape, bump or rattle, full disregard for good bends for good flow