I have a 4.6 2004 supercab 4x2 and i want to get the Flowmaster American Thunder Exhaust System - Dual Rear Exit..will i gain any HP and torque and i cant find this model for my 2004 anyone know where i could find it? it listed at $192.00 to $750.00..pretty good but i am looking for a deep sound as well as power!! Thanks

 

Well, I know the Flowmaster guys are going to be mad about this, but I put a Flowmaster 40 Series on my 2005 4.6L and it hurt my low end torque quite a bit.
Are you looking for a full system? If so the Flowmaster is the cheapest way to go. A Magnaflow is more expensive but the system is stainless steel and around $400 give or take. Also, I can feel the difference between the Magnaflow and Flowmaster from a stop. The truck would downshift frequently on hills with the Flowmaster and stays locked in OD on the same hill with my Magnaflow. I also prefer the sound of the Magnaflow. I find it smoother and deeper than the Flowmaster. Listen to both on your engine though before making a decision.

 

i have heard the american thunder on a few trucks and it sounds great(IMO) it should give you a nice boost in low end TRQ and HP over the stock system, i think you will be pleased with this choice, you should check Summit they carry a full line of the flowmaster product, good luck

 

Again, as always, I'll tell you this: Don't expect a noticeable gain in anything but gas mileage if you drive it normally. A simple bolt on exhaust mod will not gain you 20HP, or even close without several other mods.

That said, I use Flowmaster 40 series, and only Flowmaster, and I run a blown 5.4 2V

 

i have the 40 serires flowmaster with the dual outs....all custom bending and such.....but i also have the k&n intake....my feeling is that if you want the exhaust you need the intake to really get a nice boost out of it because the k&n intake brings in more air and faster so now you need to get out the exhuast faster thats where the flowmaster kicks ***....i felt a big difference with just the intake and then once i put on the flowmaster it really kicked...now im looking to do throttle body and a new maf....not really gonna get into a supercharger or anything....just simple bolt ons

 

Wow thanks guys i really appreciate the help and i think i am gonna go with the flows and mabey get a K&N intake..thanks again!!

 

Instead of the K&N intake, take a good long look at the Air Force One from Troyer.

 

OK,

I have a 2000 4.6 with the following:

K&N Intake, Jet MAF, Airraid T/B Spacer, BBK T/B, Jet Powerstat, Gibson SS Headers, Flowmaster Original 40 3in SI/SO (exit in front of pass rear tire). I also have the Hypertech P/Programer. Just adding the intake will make a big difference (trust me). All the rest can happen over time. It has taken me about 3 years to add all of the above (I'm not rich...LOL)

Any 40 series will sound good on the 4.6. Flowmaster has the catback systems (#17403 & #17417) for your model year. Try Summit Racing (good prices).

If you really want to get creative, try desiging your own system with Flowmaster's pre-bent (mandrel of course) systems (just add YOUR muffler of choice).

I'm learning that it is really up to YOU, not the guy at the muffler shop, because YOU HAVE TO LIKE IT!!!

Good Luck my freind.