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Discussion Starter #1
Hi, I have a basically stock 92 Mustang GT, it has equal length shorty headers and bassani x-pipe w/cats, bolted to mac mufflers. My question is if I cut the x-haust pipe just before the mufflers and get rid of them, the x-pipe will have about 2-3 ft of straight pipe still bolted to it and that will be my whole x-huast. Will this hurt my cars performance any, do i need the back pressure that the mufflers produce for my valve train to work properly? I am mainly doing this for the sound, and this is a daily driver. Someone please HELP! Thanks alot!
 

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Backpressure

Loseing backpressure will not hurt you if you retune your engine for it. When you relieve the pressure it usually lets more intake charge (air/fuel) in your cylinder so you must increase the timing and most likely add more fuel. Most likely anyone who says different didn't adjust the engines settings to compensate for the loss of backpressure. I can't see how leaving spent gases in your cylinders will help performance.
This Quote comes from a particular performance book I have read,
" anyone who thinks backpressure will help their engine obviously hasn't spent anytime on an engine dyno, 99% of the time you will see a power increase as long as the engine is tuned for the loss of backpressure"
I have read this in several different books and articles, but they all basically say the same thing.
And the backpressure of your engine will not effect the valvetrain, It actually has nothing to do with the valvetrain. My only questuon is, do you know how loud this is gonna be??:eek:
 

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Discussion Starter #3
cant I suck a valve if I dont have any back pressure? No I dont know how loud it will be, so i basically have to make upgrades and a trip to a dyno machine or I could lose power?
 

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You will be fine, Your valves will be fine. Now if you run the engine without any headers then you might have problems, not to mention the sonic booms coming fom under your hood as each exhaust valves opens LOL

You will be OK:joy:
 

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If you do happen to lose any power, try setting your timing up a few degrees. And maybee raising your fuel pressure up a bit if you can. If you do feel a power loss, you might even let the car adjust to it for a while before you put the muffs back on.
 

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Your EEC tables were built with either 2.3" of water backpressure (5spd) or 2.6" (AOD). If you decrease this backpressure, you change the amount of air that the factory calibration was set to (like previously mentioned). In wide open throttle (WOT) the O2 sensors do make adjustments, so you may need more fuel. You can tune this by using a fuel pressure regulator and making fuel pressure adjustments.
 
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