Originally Posted by The_Stretcher
When ever your ready go ahead and educate. ?de0a
Well you know how the feeling you get when you open up the exhaust without a tune and it feels like it lost some low end power? There isnt necessarily a lose of power as its more a shift of the power band to a higher rpm. This is because the engine can breath more freely and can better produce power from the mid range up.
On our 3.7's it translates to a huge jump in power at about 3k rpms all the way to redline. But untuned you will have a slight lag down low and the only way to correct it is with a tune. More restricted exhaust chokes the engine and it cannot breath as freely. This hurts not only power but also efficiency.
I'll use mine as an example of what effect it had. Before, when it was completely stock I got no better then 23mpg highway 17 city. Then I did a 2.5 inch catback, the intake and tb. My numbers jumped to 26/17 mpg and my 1/8th mile times came down from an 11.3 to a 10.6. Then I did the headers. The times came down to 10.37.
I followed up with deleting the cats and putting a hypertec tuner on it. And while I did lose .2 on my 60foot times I did pick up a few mph in the 1/8th and way better mpgs. I will avg 28 higway and peak at 34.5 mpg and still maintain the 17mpg city. (Before my o2 sensor went bad)
Im still running headers and no cats. Only now its true dual with 2.5 inch from the headers back. I havent been able to test mpg or track it because when I went duals I was also getting ready to pcs to korea.
In relation to a turbo engine, more "backpressure" will cause a longer spool up and have greater lag then a setup that's less restricted. Restrictions in thd exhaust slow down the exhaust flow and this hurts power. You also lose heat energy in the exhaust as well.