O.K.....I've heard and read many opinions on various true dual exhaust and single in, dual out exhaust systems. Some say the si/do system hurts low end torque....some say si/do systems HELP all around performance AND gas mileage. I want to know what the REAL deal is.

I have a 98 5.4L engine with factory exhaust. I want a nice, low rumble, and I've had flowmaster in the past, and I love the tone. I don't have a whole pile of cash to spend on a true dual exhaust system, but the si/do system seems to be a more affordable route. Does anyone here have any experience with flowmaster (or other brand) si/do exhaust, and what is your opinion of the si/do setup? Thanks in advance.

Jason

 

if you want the best all around performance. a single pipe system will not let you down. a SI/SO with 3 inch pipe will give you much better power across the board. we put a 3 inch gibson on our 5.4 and we have no low end loss. it really helped towing.

the problem with duals is most people put too big of pipes. true duals on these motors should be 2-2.25 inch pipes only. any bigger will kill low end most likely.

dual exit mufflers dont have a high chance of losing low end torque. the cats and the muffler provide lots of backpressure. but if you want a dual out muffler, then i would use 2.5 inch exits.

just my opinion on exhaust for the 5.4

 

I have true duals running off of my headers into two flowmaster 40 series si/so mufflers. my pipe is 2 1/2 in. i have noticed no loss in power and love the sound of it turned down in front of my rear axle.

 

I have a Flowmaster 40 Series SI/DO and the 4.6. I didn't notice any loss of low end, increase at any rpm, or increase in gas mileage. It pretty much just sounds and looks great.

 

Just wondering, how much more is a true dual vs a si/do Flowmaster system? To me, the true dual just makes more sense, but again I'm wondering about costs. Sound isn't THAT important to me, I'd like a nice growl, but I know that the exhaust needs to be replaced to get back some of that horsepower/torque.
I've got a brand new 2002 F150 Supercab 4.6L V8. I'm interested in sticking on true dual exhaust, but I have yet to really get down and talk to mechanics and salesmen about Flows or anything. If you had to reccomend a set up, which might you say?

A. Flowmaster 40 Deltas si/do
B. Flowmaster Force II si/do
C. Flowmaster 40 Deltas true dual
D. Flowmaster Force II true dual
E. Perhaps another brand you more prefer

I keep hearing mostly about Flowmaster, so I went and researched them first. Here's what I'm looking for: Enough growl that I can know it's a truck, but not soo much it disturbs conversation and music inside the cab. I'm looking for a system that maybe is louder outside but inside is just fine. I read up and people have posted that 40 Deltas from Flowmaster would do well, but I've also ready that Force II Flowmasters are for those that want real performance.
Think of it this way: if I get anything that's really big, loud, and look-at-me-ish, my dad will probably not approve at all, and that's a bad thing, because he's making loan payments right now.
Along these lines, the Gibson(s) might be a way to go, but I'm not sure, haven't read anything about them yet. Anyone have a good website that talks about them?
I've also read about si/do systems with pipes that are too large, and it causes the low end torque to drop. This is not what I want at all, it should all get better, not worse.
Thanks in advance for your help

 

If it's power your looking for, then the Gibson Sweptside cat-back exhaust is the big ticket. It gives you tons of torque and pulling and passing power. Plus a big HP boost. And it's Gibson's most powerful exhaust. It is a 3" si/so cat-back, and also it's Gibson's toughest exhaust for off-road truck use. It's not to loud, just a little louder than stock. But it's got a nice rumble to it. And enough growl to tell anyone it's not a stock exhaust. If you have your heart set on Flowmaster, I recommend either true duals(2-1/4") with an X-pipe, or a si/do muffler with 2-1/4" pipes exiting out back. But whatever you do, if you you choose a dual exhaust don't use anything over 2-1/4" pipe. You could loose low-end torque if you go over 2-1/4". If you want a single exhaust, 3" pipe is the way to go. It's almost 2:00 AM so I'm going to bed. Hope I helped you out.