Stock Exhaust System

Discussion on fuel delivery & intake/exhaust tech & mods.
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elc32955
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Re: Stock Exhaust System

Post by elc32955 »

I had the 8/4/8 drone issue with AFM when I first switched from stock exhaust to the SLP Powerflo axleback set I'm running right now. The tone is exactly one octave lower when it does the flip to 4 and then one octave higher on the flop back to 8. HOWEVER.... when we took the exhaust apart doing my 3.45 swap last year we must have changed something in the system ever-so-slightly, as the drone lessened by over 50%. I'd say it's now much more palatable, or perhaps I've just gotten use to it. I was contemplating installing a J-pipe to try to get the noise down before, but now it's not worth it.

Of course we may have to re-visit when I get headers on and gut the rest of the stock exhaust, but for now it's a happy compromise I'd say. I can't go too loud as the wife drives the car as much as I do and she has somewhat limited tolerance for a good performance exhaust..... sigh....

Oh, had not noticed on the tranny simplicity to drop as I've not needed to do it yet. Hopefully I'll never have to visit that part of the car's anatomy.

Eric
System Manager and your tour guide for the day. 2015 Caprice w/LFX, former NC DPS staff car. Partial hybrid G8/SS/Camaro SS interior mods, SS MyLink radio upgrade, 2016 Camaro V6 rims, GMPP Malibu chrome exhaust tips, otherwise bone stock for now.
ImpalaPPV
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Re: Stock Exhaust System

Post by ImpalaPPV »

The 3.45 gears raised the RPM range which changed the sound while driving. I'm trying to figure out how much disabling AFM would affect mileage. Is improved sound worth the drone on the highway with AFM for mileage? Or, is a loss of 1-2 mpg worth the elimination of drone and improved sound?
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elc32955
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Joined: Thu Nov 29, 2012 10:32 am
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Re: Stock Exhaust System

Post by elc32955 »

Well there is another consideration as well, with 3.45's the car is a lot more responsive IMO. If it wasn't for the stupid CAFE standards GM probably could have made that the standard gearing for the PPV. I guarantee you I can still do every bit of the 159 MPH top end with my current gearing if I had a mind to. 3.70's would eat into the fuel economy too much I think. Fuel economy is a consideration if you drive frequent start/stop patterns every day vs. a lot of commuting miles on the highway. I routinely still see lower 20's on my fuel economy after the gear change with my AFM still enabled. I think if I could routinely fill with non-ethanol gas it would help. It's hard to find those pumps here in Florida and when you do it's routinely priced at $1.00/gal over the prevailing premium price. But it is available if you want to seek it out.

Hard choice to make. But.... you have to pay a little to play.
System Manager and your tour guide for the day. 2015 Caprice w/LFX, former NC DPS staff car. Partial hybrid G8/SS/Camaro SS interior mods, SS MyLink radio upgrade, 2016 Camaro V6 rims, GMPP Malibu chrome exhaust tips, otherwise bone stock for now.
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