It's not even that specific. If you relieve too much backpressure, you'll lose
power. If you have too much backpressure, you'll lose power. Finding the sweet
spot is part science, part black art. So far, we know that for a stock to mildly
modified engine, a single 3" is really nice. To go larger, you'd better have
serious engine work (I think the ViperTruck has 3 1/2" or 4", but Austin has more
than a little work on that thing).
Once you get into duals, things get even trickier. Stock, I think you've got a
2.5" pipe, which works out to 4.90625 sq. in. cross-section. Dual 2" pipes have
a total cross-sectional area of 6.28 sq. in. Dual 2.5" is 9.8125 sq. in. A
single 3" is 7.065 sq. in. A dual 3" is 14.13 sq. in. So a dual 3" will leave
you with precious little backpressure, and your truck will be a slug. 2.5" is
probably the largest you can safely go on duals, and 3" on a single pipe,
without major engine work. I know quite a few people are running a Gibson
dual-exit on their V8s with good results.
If I'm all wet here, please let me know, folks.
Paul Macey wrote:
> On Thu, 6 Sep 2001, Sterling wrote:
>
> > Stick with flowmaster, I got a Ravin, it sounds great outside but the incab
> > noise level is nearly unbarable. And who says you can't put a 3" on any
> > model of Dakota?
>
> I thought it depended on single -vs- dual exhaust, and for the 4.7, a dual
> 3 inch exhaust would actually rob you of power and decrease HP and/or
> torque.
>
> For best performance gains for the 4.7, believe the common thought is to
> go with a 3 inch single exhaust.
>
> Now as regards to gibson -vs- flowmaster on the single exhaust, I've seen
> quite a few posts saying people were disappointed with the gibson (not
> much louder than stock) and took them off and re-installed a flowmaster
> setup.
>
> > ----- Original Message -----
> > From: <s_villaire@yahoo.com>
> > To: DML <dakota-truck@buffnet.net>
> > Sent: Thursday, September 06, 2001 8:21 AM
> > Subject: DML: Aftermarket Muffler Options
> >
> >
> > >
> >
> >
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