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Guest Message by DevFuse

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Bad gas mileage after slp loudmouth install?

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4 replies to this topic

#1 chadster54321



  • Northeast Region
  • 153 posts
  • Region:U.S., Northeast
  • Current Vehicle:2013 Boss 302
  • Boss 302's Year:2013

Posted 01 December 2016 - 11:48 PM

Alright so i noticed a huge difference in mpg and no i been baby footing for the past few days to see if it is my driving habit and it is not. I am wondering if its an exhaust leak or because i didn't disconnect the negative battery terminal to reset and relearn. Which it told me to do in the instructions. But I had no idea if that coukd cause an issue due to cars being self learning. Im going to disconnect my battery tomorrow while im at the shop at work and see if anything happens. Any opinions or advice is welcome. But like i said this is very noticeable. I know for a fact when it says im getting 21 mpg highway the whole time when it feels more like 15 mpg. That and i drove 50 miles today and my gas gauge read like i just drove over that. This is highway to highway when i got on it and then off it. Went from 145 till empty to 65.
  • paskellusmc likes this

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#2 302 Hi Pro

302 Hi Pro

    Boss 302 Builder

  • Moderator
  • 4,348 posts
  • Region:U.S., Northeast
  • Current Vehicle:2012 KB Boss 302 Mustang
  • Boss 302's Year:2012

Posted 05 December 2016 - 11:23 AM

Wow, that is a significant change. I suspect you may have better results after the reset. Keep us posted on the results.

Thanks for sharing this.

2012 KB Boss 302 MC: 500A | Boss Production Line Assembly Number 2800. Vehicle Special Ordered with Recaro Sport Seats & 3.73:1 Torsen Option | Engine: FRPP 84.5MM TB, Peterson CJ Vent Can, TracKey Activated, AirAid CF PJ CAI, FRPP 84.5MM TB | Drivetrain: AE 4.0" Aluminum DS, MGW Gen 3 Race Spec Shifter, GT500 Clutch Pedal Box, FRPP Stainless Clutch Line, Dedicated Clutch Fluid Reservoir, FRPP Trans Cooler Scoop. | Exhaust: Silver Ceramic Kooks Super Street Headers, MagnaFlow Street/Comp 3.0" SS CB X-Pipe System, Open Kooks SS Boss Side Pipes. | Suspension: FRPP "T" Springs (alternate Steeda Boss Rear Springs), Koni Sports (Yellow) Adjustable Struts/Shocks, Steeda HD Camber Plates, Cortex Watts Link, Steeda Billet KB Poly/Spherical LCA's, KB LCA Relo Brkts, Steeda Adj. UCA & Energy Suspension Sys. Upper Diff Housing Bush, OEM Boss Rear Sway Bar | FRPP GT500 Forged wheels, (19X9.0 F & 19X10.0" R) | Brakes: FRPP Boss 302 Cooling Duct Kit, Steeda SS/Kevlar Brake Lines, GT500 13.8" Rear Rotors, GT500 Rear Brake Pads, Dot 4 Motul 600 HT Fluid | Body: FRPP Boss 302S Grill, FRPP Boss 302 LS Front Splitter, FRPP GT500 Rear Spoiler & Serviceable Gurney Strip, BFR Front Tow Hook, Jacking Plates, 3M Window Tint, (35/20), OEM Boss 302 Floor Mats & Boss 302 Car Cover, Pioneer TS-D6802R Speaker System, Auto Dim, Home Link & Compass Mirror. Notes: Current Intake System - Ram Air thru Front Grill Fog Light, OEM CAI Box and AEM Aluminum Intake Tube with Drop-In High Flow Filter. In Testing Spring 2016. SCT-X4 Tuner used exclusively for Data-Logging AFR/Timing Curves Only. FRPP TracKey is Preferred PCM Tune.

#3 chadster54321



  • Northeast Region
  • 153 posts
  • Region:U.S., Northeast
  • Current Vehicle:2013 Boss 302
  • Boss 302's Year:2013

Posted 05 December 2016 - 01:34 PM

Yes it was and i been driving it after the reset and i got hell of a lot better fuel mileage. Lesson learned haha. FOLLOW INSTRUCTIONS TO THE LETTER! Lmao

#4 paskellusmc


    New Boss 302 Member

  • Southeast Region
  • 2 posts
  • Region:U.S., South Atlantic
  • Current Vehicle:2013 Mustang Boss 302

Posted 11 September 2017 - 10:12 PM

Looking to purchase the SLP muffler deletes for my almost completely stock 13 Boss 302.
Any regrets? How much of a difference?

Thanks. -Jacob (13 Boss 302 GHIG)

#5 Rich B.

Rich B.

    Not another year gone by?

  • Northeast Region
  • 3,651 posts
  • Region:U.S., Northeast
  • Current Vehicle:Boss 302 and '16 Buick LaCrosse
  • Boss 302's Year:2013

Posted 12 September 2017 - 04:42 AM

Maybe too loud with open side pipes. Don't think I could get away with that even in ME. Mine (not SLP) are straight through with no drone and only loud when I want them to be or at first startup.

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