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Thread: How Restrictive are the stock Mufflers? This much.....

  1. #1
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    Default How Restrictive are the stock Mufflers? This much.....

    Did a little work to the car this past week.

    a) Strapped it to a local dyno for baseline then again after the work.
    b) Kid there had the "brilliant idea" of pulling off the mufflers to get another dyno run comparison point
    c) Holy cow - the stock mufflers are massively restrictive!
    2009 G8 GT
    ARH Long Tubes 1 7/8" / Magnaflow Mid Muffler / Cherry Bomb Vortex Mufflers / Magnuson Supercharger 1.9 / Ported blower base / 2.8" Pulley / LS3 rockers with Trunion upgrade / Trick Flow LS3 cylinder heads / Overdrive "non-cog" pulley system / 8-Rib Pulley system / ATI Super Damper / DOD Delete / Lunati Lifters / Custom Patrick G Cam Grind / Wiseco Forged Pistons / Injector Dynamics 85lbs / 4" RotoFab Intake Tube / 90mm MAF Tube / VMax 90mm Ported Throttle Body / LS7 MAF Card / ZL1 Fuel Pump / JMS Fuel Pump Booster / VaporWorx Controller / B&M Tranny Cooler with fan / Circle-D Heavy Duty Rebuild & 265mm triple Disc Billet Converter / Camaro Tranny Pan / Custom Engine & Tranny Tune by Patrick G / Eibach Lowering Springs / BMR Front & Rear Sway Bars & LCA's / Moog Front Control Arms / DBA 4000xs Rotors / Hawks Ceramic Pads / Breyton BE Wheels

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    VIP Member Kermit's Avatar
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    WOW, Looks like you need to get some after market mufflers there Henry!!!!
    2009 G8 GT MGM.
    Performance - 1900 MagnaCharger , Lunati Cam, RCR Ported Heads, Intake and TB, FAST #65 Injectors, CTS-v fuel pump, Kooks 1 3/4" LT and Catted X-Pipe, Pypes Violator Axel-Back, Roto Fab CAI, RX Oil Catch Can, Pedders XA's & Track II Bushings, BMR Sub Frame Connectors, Sway Bars & Rear Control Arms, 19 Inch Staggered (8.5 front/9.5 Rear) VMR 810 Wheels, DBA 4000 Sloted Rotors with Hawk HPS Pads & Russels Brake Lines, Camaro 3.27 Diff, Gforce Axles.
    Cosmetic - Partially De-badged Rear, 6.0L Badges, Tinted Side, Rear Markers & Tail Lights, 35% Tint, Auto-dim Mirror, Spencers 6K 35W & 5K 25W Fog HIDS, Blacked Out Door Chrome, Vagas Nates 3 Gauge Pod W/Interceptor Gauges, Color Matched GXP Diffuser, Shark Fin Antenna, V-LEDs on Side/Rear Markers, Brakes & Back Ups Lights, MM Carbon Fiber Rear Spoiler


    1/4 mile 10.917 at 130.44mph 564 RWHP 568 Torque.

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    VIP Member G8 GT V8's Avatar
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    Holy sheeeet!!! Guess they become way more restrictive at your horsepower level. For us with the mild builds, probably not as much to be concerned with, but damn that made a big difference. Thanks for sharing this info...
    Marty

    G8 gone, but not forgotten...

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    It sure as hell got my attention! :-). I'm going the Magnaflow mid muffler and Cherry Bomb Vortex route. I was "floored" at leaving 49 ft lbs of torque on the table - and in my sweet spot of daily driving rpm! Yikes Batman!


    Sent from my iPhone using Tapatalk
    2009 G8 GT
    ARH Long Tubes 1 7/8" / Magnaflow Mid Muffler / Cherry Bomb Vortex Mufflers / Magnuson Supercharger 1.9 / Ported blower base / 2.8" Pulley / LS3 rockers with Trunion upgrade / Trick Flow LS3 cylinder heads / Overdrive "non-cog" pulley system / 8-Rib Pulley system / ATI Super Damper / DOD Delete / Lunati Lifters / Custom Patrick G Cam Grind / Wiseco Forged Pistons / Injector Dynamics 85lbs / 4" RotoFab Intake Tube / 90mm MAF Tube / VMax 90mm Ported Throttle Body / LS7 MAF Card / ZL1 Fuel Pump / JMS Fuel Pump Booster / VaporWorx Controller / B&M Tranny Cooler with fan / Circle-D Heavy Duty Rebuild & 265mm triple Disc Billet Converter / Camaro Tranny Pan / Custom Engine & Tranny Tune by Patrick G / Eibach Lowering Springs / BMR Front & Rear Sway Bars & LCA's / Moog Front Control Arms / DBA 4000xs Rotors / Hawks Ceramic Pads / Breyton BE Wheels

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    Never would have thunk it would be that bad.

    Rotohack 102 intake - 102 MAF - TPIS 102 TB - TVS1900 ported & plated w 8 rib 2.5" front + OD rear
    RCR ported heads - RCR Lunati 219/231 113+1 - LSA Crank - Molnar rods - Racetec pistons
    Kooks 1 7/8 LT - Solo 3" CB - 3.27 diff w WaveTrac MT DRs + M&H FRs on Weld RT-S
    CTS-V fuel w Vaporworx - FAST 85s - Alkycontrol meth M15 + M10 - RCR tune
    Old 10.09@138.8 1.51 60'
    New ?@? 716 rwhp 652 rwtq

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    From PatG back in 2010
    9.5 RPM (Red Passion Metallic)
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    "If the women don't find you handsome, they should at least find you handy"-Red Green



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    Beyond Help gr8lover's Avatar
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    Suprised you still have stock muffs.... but yea thats alot!!1

    I dont think people have a clue on how much power can be killed with undersized exhaust.....

    I just recently put on 3" muffs instead of the 2.5" mufflers I had... (had a full three inch system going down to 2.5" muffs...)... ARH and other shops said it wouldnt make much of a difference..........

    After I did it, I went from 835rwhp to 921 rhwp...... i was absolutely shocked!!!!!!!
    2009 G8 GT; F1x procharger on Supercharger store direct drive system; 430cuin LSX; E85; 9" rear; DSS once pc driveshaft; 4L80
    9.2@151.... fastest and heaviest G8 known to man.... ...

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    Quote Originally Posted by hflores3 View Post
    Did a little work to the car this past week.

    a) Strapped it to a local dyno for baseline then again after the work.
    b) Kid there had the "brilliant idea" of pulling off the mufflers to get another dyno run comparison point
    c) Holy cow - the stock mufflers are massively restrictive!
    you really drive your car with the gas pedal FLOORED between 2700 and 4200rpm ?

    you would only be using that range floor at the track , not on the street in normal average conditions

  9. #9
    Beyond Help gr8lover's Avatar
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    Quote Originally Posted by s/c'd cav View Post
    you really drive your car with the gas pedal FLOORED between 2700 and 4200rpm ?

    you would only be using that range floor at the track , not on the street in normal average conditions
    ..when he accelerates from a stop light he will have more power...... ... not sure what your point is.... he will be in that power band even accelerating from a light or cruising then hitting the gas...
    Last edited by gr8lover; 03-15-2015 at 12:51 AM.
    2009 G8 GT; F1x procharger on Supercharger store direct drive system; 430cuin LSX; E85; 9" rear; DSS once pc driveshaft; 4L80
    9.2@151.... fastest and heaviest G8 known to man.... ...

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    Quote Originally Posted by gr8lover View Post
    ..when he accelerates from a stop light he will have more power...... ... not sure what your point is.... he will be in that power band even accelerating from a light or cruising then hitting the gas...
    well since when have you ever seen anyone on a dyno , test in your average daily driving use ?

    ive seen it done , NOT NEVER EVER !!!!!!

    so in the real world , all the dyno is showing he will loose time(ie slower) at the track , so it shows nothing on how the car is driven in light throttle use

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