I am currently running LT's, high flow cats and 2-14" 40 Series Flows. Im going back to Magnaflow after being tired of the drone from the 2 Flows and Im wondering if anyone has gone with two Magnaflow 4"X9"X18" 2.5/2.5? I know that there are alot of guys running 14", but havent seen many 18". My biggest priority is reducing highway noise, so my thought is either 18" or 20-22".

 

That is a tough call with LT. I would think go with at least 18" depending on how much quieter you wanted it. How much louder was it after the LT install?

14" will still be quieter than them 40's though, but not by too much...

 

The LT's, cats, X pipe and duals all went on at the same time so I think you can guess how much it changed from stock. I still want a good sound, Im just tired of the highway drone. I want it to be a little more highway friendly since highway is what I drive most. The last truck I had I ran a DI/DO 18" and it really wasent too bad, but I dont know if thats really a good idea with the other exhaust mods I have.

Borla is not out of the question either if you have any suggestions on those. Thanks for your help.

 

Borla Pro XS it is then! I replaced a pair of 40's for these and will never look back. I run no cats, check out my videos. I would love to hear these with LT's, but it might be a hair louder than what you are looking for. I also have an old video with the flows so you can compare the noise level difference between the 2 different mufflers.

 

I agree, Borla Pro XS is a top notch muffler and should fit your needs. Should add some torque too over those baffled flows.

 

what length Borla Pro's are yall running?

 

Go for the 18" Borla ProXS, or 18" Magnaflow. The Borla will sound a little nicer, it wont open up a higher pitched volume at WOT like Magnaflows do.

 

So the Borla will not create alot of drone at highway speeds? Ive owned magnaflow before and know that highway noise is very minimal, but Ive never driven a truck with Borla mufflers. I dont mind it being loud at WOT or acceleration.

 

The Borlas will sound the same inside as Magnaflows, actually a slight pinch quieter inside since they are durable t-304 thick stainless with thicker packing. The main point to make it calm in cab is to have the entire muffler mounted under the bed of the truck, not one inch under cab.

 

All si/so Pro XS mufflers are 14". 19" is for si/do.

http://www.borla.com/proxs/pages/mufflers.php

You could also run 2 16" XR-1 mufflers, but they are a bit higher...

 

I have both under the bed now, but I do have a SCrew and yall are both driving SCab. I didnt think about it earlier, but I bet yall have less cab noise than me since there is more room to mount the mufflers farther back. I believe here in my part of TX it wont pass inspection with out the muffler being past the cab anyway. Thanks for all of yalls help. I really appreciate it. Since I can only get an 18" in magnaflow, Im kind of convinced on those. I think 18" will be a good sound and performance improvement over the flows.

 

That does add in but very minorly. My truck drones real well with its system but its barely noticeable when on the highway or riding through town.

 

For the Magnaflow 18", there is a 4 X 9 body and a 5 X 8. Is there any performance or sound difference in a different sized body or is this just to meet space requirements in some vehicles?

 

Just fitment issues. There isn't any real audible change or tone change.

 

Just an update. Thanks for all of yalls help. I ended up with the 2-18" Magnaflows and it sounds perfect. Even with my LT's and cats, the sound is very minimal at freeway which is what I wanted. The best part about the swap was that I feel like I gained alot of lost hp and tq. I never thought the power would feel this different going from a flow to a mag.