Backpressure. Is it needed?

whtstang97 · July 5th, 2008, 06:33 PM

I have a 97 mustang gt with regular bolt ons, in sig, i have right now dynomax mufflers but only half way, no tips, on 2 1/2 inch pipes. I was wondering if i put the slp loudmouth with the same way only half way will there be a lack of backpressure? I hear they are pretty hollow in mufflers. also will this reduce me in power in the quarter mile? Thanks you guys.

DeMello · July 5th, 2008, 06:46 PM

i forget how it works exactly but its defintily not gonna make you slower

i think wat i was told was you lose a little bit down low but make it all in the high rpms

it could be different since your NPI but i dont think that should have to much of an affect on it

97GT4.6 · July 5th, 2008, 08:11 PM

You might lose a little back pressure, but i don't think it will be noticeable. It's more of a big deal on V6 stangs. I'd go for it

BlackSunshine · July 7th, 2008, 05:24 AM

I took the mufflers off my stang and ran side pipes from the cats back and I lost alot of torque.. That was with my 98 GT. It ran like garbage when I did that so I put the mufflers back on and ran mine this way BBK headers, High flow BBK cats, BBK H-pipe, 40 series flowmasters and dumps right after the mufflers and that made it run like a champ... IMO yes backpressure is a issue..

stanglifemike · July 7th, 2008, 12:40 PM

You lose torque, but gain hp. So a little less down little and a little more up top. If your racing from a roll or just cruising it will be to your advantage.

TurboLX · July 7th, 2008, 12:41 PM

Exhaust Theory

Exhaust theory and design - Mazda3Club.com

whtstang97 · July 7th, 2008, 11:48 PM

Thanks for the info guys. I think the slp mufflers will work out plus i'll give the loudness without having to get cut outs.

Trick Tuners · July 8th, 2008, 01:29 PM

Exhaust backpressure is a total myth. Its all about exhaust velocity.
exhaust back pressure myth - Google Search

ModMustang97GT · July 8th, 2008, 05:30 PM

Ok, exhaust back pressure is not a myth. It is needed on Naturally Aspirated engines. It aids in the scavenging of your cylinders, as well as with the engines computer. However, to give you an idea of how little you need. I used to run open headers around town for several months. With LT's you have all the Back pressure you need for the car to run correctly. You do gain HP and lose a little bit of Torque. But I couldn't even tell the difference to be honest. And as long as your tuned to ignore your O2's. (Yes ignore. They are too close to the end of the exhaust when you have open headers for it to read correctly. You have to have a very specialized tune) You can run like that all day. And every girl in town will look your way and can't help but smile because muscle cars make them giddy.

stanglifemike · July 9th, 2008, 11:22 AM

+1
Especially to the last sentence

July 5th, 2008, 06:33 PM	#1
whtstang97 Newbie 1997 Mustang Gt 14.0 @ 99mph Join Date: Apr 2008 Location: Texas Posts: 35	Backpressure. Is it needed? I have a 97 mustang gt with regular bolt ons, in sig, i have right now dynomax mufflers but only half way, no tips, on 2 1/2 inch pipes. I was wondering if i put the slp loudmouth with the same way only half way will there be a lack of backpressure? I hear they are pretty hollow in mufflers. also will this reduce me in power in the quarter mile? Thanks you guys. __________________ 3.73 Gears, Mac pulleys, CAI, Short shifter, Intrax Springs 14.0 @ 99mph

July 7th, 2008, 05:24 AM	#4
BlackSunshine StoppingTerrorOneBombAtATime 1998 GT, 2005 skittle 1/8 mile: 8.78@89mph Join Date: Jan 2007 Location: In yo strip club takin all yo biotches.. Posts: 797	I took the mufflers off my stang and ran side pipes from the cats back and I lost alot of torque.. That was with my 98 GT. It ran like garbage when I did that so I put the mufflers back on and ran mine this way BBK headers, High flow BBK cats, BBK H-pipe, 40 series flowmasters and dumps right after the mufflers and that made it run like a champ... IMO yes backpressure is a issue.. __________________ MM Sapper squad: Founder MM 4 Banger club: Co-Founder

July 7th, 2008, 12:40 PM	#5
stanglifemike MM Fanatic 06 GT & 98 GT Join Date: Dec 2006 Location: Douglasville, GA Posts: 3,320	You lose torque, but gain hp. So a little less down little and a little more up top. If your racing from a roll or just cruising it will be to your advantage. __________________ 98 GT: Accufab, Steeda, BBk, Mac, FlowMaster, Moser, Ford Racing, American Racing, Nitto DR's, Eibach, SCT, FPS 06 GT: JLT, SCT, FRPP/Borla, Pypes, Steeda, BamaChips, BMR RadMustangs Store

July 7th, 2008, 11:48 PM	#7
whtstang97 Newbie 1997 Mustang Gt 14.0 @ 99mph Join Date: Apr 2008 Location: Texas Posts: 35	Thanks for the info guys. I think the slp mufflers will work out plus i'll give the loudness without having to get cut outs. __________________ 3.73 Gears, Mac pulleys, CAI, Short shifter, Intrax Springs 14.0 @ 99mph

July 8th, 2008, 01:29 PM	#8
Trick Tuners Authorized Vendor KB'd GT Join Date: Nov 2006 Location: San Diego Posts: 1,124	Exhaust backpressure is a total myth. Its all about exhaust velocity. exhaust back pressure myth - Google Search __________________ SCT Custom Tuning, JLT intakes, Aeroforce Interceptor OBDII gauges and PLX wideband products @ Trick Tuners email joe@tricktuners.com PM for super MM member deals! Super Cheap Motorsports Camera to record the Action!

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July 5th, 2008, 06:46 PM	#2
DeMello Banned 01 nitrous injected GT 12s next time out... Join Date: Apr 2008 Location: Florida Posts: 3,912	i forget how it works exactly but its defintily not gonna make you slower i think wat i was told was you lose a little bit down low but make it all in the high rpms it could be different since your NPI but i dont think that should have to much of an affect on it

July 7th, 2008, 12:41 PM	#6
TurboLX Banned 1990 Mustang LX Turbo 9.71@141.6 mph Join Date: Oct 2006 Location: NY Posts: 8,783	Exhaust Theory Exhaust theory and design - Mazda3Club.com

July 8th, 2008, 05:30 PM	#9
ModMustang97GT Enthusiast 1997 Mustang GT Join Date: Aug 2007 Location: Seattle, WA Posts: 681	Ok, exhaust back pressure is not a myth. It is needed on Naturally Aspirated engines. It aids in the scavenging of your cylinders, as well as with the engines computer. However, to give you an idea of how little you need. I used to run open headers around town for several months. With LT's you have all the Back pressure you need for the car to run correctly. You do gain HP and lose a little bit of Torque. But I couldn't even tell the difference to be honest. And as long as your tuned to ignore your O2's. (Yes ignore. They are too close to the end of the exhaust when you have open headers for it to read correctly. You have to have a very specialized tune) You can run like that all day. And every girl in town will look your way and can't help but smile because muscle cars make them giddy. __________________ Aztec Gold 97GT. MM CC Plates, Panhard Bar, Subframes & Tower Brace Eibach Sway Bars H&R Race Springs/Bilstein Shocks MAC CAI, LT's, Catted H and Pro-Dumps KB Boost-a-Spark PI Swap Spun Main Bearing...

July 9th, 2008, 11:22 AM	#10
stanglifemike MM Fanatic 06 GT & 98 GT Join Date: Dec 2006 Location: Douglasville, GA Posts: 3,320	+1 Especially to the last sentence __________________ 98 GT: Accufab, Steeda, BBk, Mac, FlowMaster, Moser, Ford Racing, American Racing, Nitto DR's, Eibach, SCT, FPS 06 GT: JLT, SCT, FRPP/Borla, Pypes, Steeda, BamaChips, BMR RadMustangs Store

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