Other than GT 500 Mufflers and a VMP tune my 5.0 is stock. Over the winter I put a Magnaflow after cat 3" X pipe on. Took it back to the track this spring and the car ran pretty much the same as the stock H. 12.37 with H and 12.39 with X. MPH was also down .11. My other concern was my daily mileage was down from 17.8 to 17.4. Weather was more favorable at the track so I expected some better ETs with the 3" X vs stock pipe but the mileage supported the X might have done more harm than good. Jason at VMP said I didn't need a new tune for the X. Anyone else see similar results?
Stock H pipe vs Magnaflow 3" X
- Thread starter viperakron
- Start date
Air was much better and temp was 20 degrees lower than previous track day. Car would of picked up a tenth vs last time at track with old H pipe. And a half a mile per gallon is more than negligible.
If your mph was only down 0.11, than you're car is making the same power it was before. And if you didn't remove the cats, it makes perfect sense. They are the restriction, not so much the pipe after. These cars are closed loop remember. So the tune will adjust for weather conditions. The better air and 20 degrees probably didn't have a huge effect. Well it obviously didn't because you trapped the same exact thing essentially. And the mpg difference is negligible. You could have a little less air in 2 tires, maybe it was windy that day. 17.8 to 17.4 is really not enough to accurately quantify a difference. Maybe a fine tune on the X pipe would give you 17.8 again.
After cat x/h pipes are worthless.
This ^^^ Either go O/R or or leave it alone unless you want to change the exhaust tone.
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