hey all,
i am just curious to know the actual benefits of having true dual exhaust on a 5.4L engine. my '99 Lariat has 2.5' exhaust leading to two flowmaster mufflers and i do not notice a dramatic difference at the pedal. what might the actual HP gains along with other positives be?? thanks for any advice.

 

HI!... Well I'm sorry to say if your running two FLOWMASTER mufflers on your truck that you probably lost power not gained it. Most likely in the low end power department. I had a true dual exhaust set-up with FLOWMASTER mufflers on my modded 5.4 and thought I noticed a increase in power but was wrong. I then switched to a true dual exhaust set-up wit MAGNAFLOW mufflers and "X" pipe and noticed a HUGE power increase over the FLOWS. It was REALLY noticable in the low-end power. Also my FLOWMASTER alminized mufflers only last 2 years tops. They were always rusting and cracking. I had to have them welded several times. After this, I will never buy another FLOWMASTER product again. Others are just now having problems with their flows too.

 

As mentioned, Flowmaster is not a company that focuses on performance. They are known for their distinct tone which is why 95% of people buy it. Borla, Bassani, and Magnaflow are better at designing performance systems with different tones. Magnaflow offers a couple new dual systems if you'd like, a SIDO #15749 and a true dual with built-in X-pipe suggested for Harley Davidson F-150's #15772. However, I believe you'll get a little more performance out of a 3" single system and replace the factory y-pipe as well.

Troyerperformance has all the Magnaflow kits at great prices.

 

I agree, Magnaflow is the way to go! I've had the Flowmaster set-up for two years and I'm tired of the increasing noise

I'm in a bad mood, my headgasket leak is back for the second time!!!

 

More then Likely it was the "X" Pipe that netted you the increase in power and not so much the Magnaflow Mufflers!

I've had nothing but Flowmasters on both my Mustangs that I've owned and gained nothing UNTIL adding a Bassini X Pipe!

Running True Duals on a Pickup without an H or X pipe will make you loose HP no matter what brand Muffler you Choose!

-Adam

 

HI!... Adam_01_F150 : I agree that the "X" pipe gave me more low-end TQ v.s my FLOWMASTER set up but that's it. But when it comes to mid range/topend power the MAGNAFLOW mufflers blow the crappy FLOWMASTERS away. I have run basically every exhaust set-up you can think of over the years on different vehicles and to this day the MAGNAFLOW mufflers are the best I have had. I like them so much that the FLOWS on my PRO STREET FORD RANGER were sold and I'm going to install MAGNAFLOWS on it now. Everybody like FLOWS because of the way they sound, they don't realize that in REAL WORLD testing that FLOWMASTER mufflers are not very free flowing. FLOWMASTER just markets them on their sound quality. A buddy of mine had a set on his MOPAR and when he replaced them with MAGNAFLOW mufflers his 11 second car dropped off 4 tenths in the 1/4 with just the muffler change. IMO FLOWMASTER mufflers are all out garbage and I will never buy another one again.

 

I totally agree with you Neal.

Plus, I am really liking the sound of my Magnaflow. With the supercharger on there, it makes it sound like open pipes. Extremely tough sounding .

 

Thanks for the replies fellas....

I'm not saying that the magnaflows aren't good mufflers in fact I agree they are probably the best out there along with Bassini and Borla as far as performance go!

BUT there performance gains are only within 5-10 RWHP Increase over Flows....If you don't believe me pickup any Muscle Mustang and Fast Ford or 5.0 and Superford Magazine....They've dynoed all the big muffler brands and the TRUTH be KNOW not much different between the Catback setups besides sound.....The Point I'm trying to make is you cannot compare True Dual Setup w/out X or H pipe vs True Dual Setup with X or H....NO COMPARISON!

Have you ever Dyno'ed a vehicle after dropping money into aftermarket parts.....I have...It will break your heart!

Advertised HP and REALWORD HP are totally different! And the Seat of Pants O'meter is wrong more than its right!

I had a 2000 GT that I dyno'ed after doing a buch to it and man was I heartbroke to only have 240 RWHP and 293 RWTQ!

-Adam

 

I feel that is quite a difference in hp when you are paying just about the same in price.

 

HI!... Just remember that the 5.4 responds WAY better to mods than the 4.6. This has been proven over and over again here on this site. Look at my truck, with just simple bolt ons I've gone from 16's to high 13's in the 1/4 and am still N/A. I've seen people dyno flowmaster mufflers on 5.4 F-150's and they all lost power over the stock muffler. The LIGHTNING guys have also gone through all the mufflers and MAGNAFLOW was one of the only mufflers that gave a RWH.P gain on them.

 

Wow....They Lost HP???

Ok I'm sold! Magnaflow Catback for me then! I knew the Magnaflows were better but I haven't heard anybody say they dyno'ed em and showed what they really gained...but then again...I have been in the Mustang Sene and not really keeping up with the Trucks......I just wish the Magnaflows were louder. The setup I have is a Race Muffler 10 Series Straight Through Design....I wonder If I lost any HP by adding this, It certainly don't feel like it, but we all know how much we can trust the Ol'Seat-O-Pants-A-Meter!

I guess I'm just gonna have to get a Magnaflow and Cut-Out these d4mn Cats!

Thanks for your help!

-Adam

 

Ummm your gallery says 14.5 in the quarter...maybe you should update that with your newest fastest time!

-Adam

 

Magnaflows can be pretty loud. But, it's a different noise than what flows make. With the addition of my supercharger, and just a magnaflow muffler added, it is extremely loud. If anyone is riding in the bed of the truck, it will hurt their ears. It really get's attention when it's floored. And that's with the stock cats still in there. Just wait until I get some high flowing ones.

 

HI!... Adam_01_F150 : That 14.5E.T was run over 2 years ago.

Here is some pics of the exhaust set-up I custom built for my truck. It uses JDM/KOOKS LT headers and the rest is MAGNAFLOW. Everything is 304 stainless steel including all hardware.

https://www.f150online.com/galleries...-793-29799.jpg
https://www.f150online.com/galleries...-793-29796.jpg
https://www.f150online.com/galleries...-793-37312.jpg

 

Neal.....Very Nice setup you have under that Beast! I bet it sounds great with those LT's!

Did you install the LT's yourself or have it done at a shop? I remember what a pain LT's or even shorties are for 4.6 Mustangs.....Is is the same way with the 5.4....Big Pain for not much Gain?

Thanks for the Pics!


-Adam