I am putting a 390 in a 71 f100 and im running open headers which muffler would give me a better sound and a lil more hp. I was thinking glasspacks. New to the site btw

 

Dynomax or Magnaflow. Stay away from Flowmasters. JMO.

 

Welcome to FTE. I have all stock exhause on my truck accept muffler. I have 1 glasspack and 1 flowmaster 40 and i have the flow on it now because it sounds better in my ears.

Also instig8r just wondering why you dont prefer flowmaster?

 

A while back one of the guys on 460ford.com did a muffler comparison on a dyno using the same motor with various popular mufflers. Magnaflow and Dynomax were among the best performing mufflers, while the Flowmasters were among the poorest and actually hurt performance. Not to mention the dreaded Flowmaster drone at cruising speed. Some of the guys nicknamed them "Slowmasters".

 

broaderperformance.com/muffler_flow_tests.htm (Independently tested cfm flows of the more popular mufflers, glasspacks and resonators @ 15” wc:
2 ½” diameter straight pipe 521
2 ¼” diameter straight pipe 365
2” diameter straight pipe 283
2 ¼” diameter tailpipe 268
2 ¼” round glasspack- no louvers 274
2 ¼” round glasspack- with inward punched louvers 133
2 ¼” round glasspack- inward punched louvers/installed backwards 141
2 ½” inlet/outlet Dynomax SuperTurbo 268
2 1/4” inlet/outlet Thrush CVX 260
2 ½” inlet/outlet Flowmaster 2-chamber 249
2 ¼” inlet/2 ½”outlet Cherry Bomb turbo 249
2 ¼” inlet/outlet Flowmaster 3-chamber 229
2 ¼” inlet/2 ½”outlet Maremount Super C (OEM Replacement) 149
2 ¼” inlet/2” dual outlet Maremount 183
2 ¼” inlet/outlet California Turbo 229
2 ½” inlet/outlet Hooker Aerochamber 324
2 ½” inlet/outlet Hooker MaxFlow 521
2 ¼” inlet/outlet Maremount Cherrybomb Vortex 298
2 ½” inlet center/outlet offset Borla Turbo 373


muffler shootout test done by CAR CRAFT

MUFFLER Flow at 28-in H20
DynoMax Race Magnum 528.64 cfm
Thrush Magnum Glasspack 507.40 cfm
Summit Fully Welded 343.38 cfm
Flowtech Afterburner 342.20 cfm
DynoMax Super Turbo 333.94 cfm
Hooker Competition 232.46 cfm
Hooker Super Competition 320.96 cfm
Summit Turbo 331.16 cfm
Thrush Boss Turbo 297.36 cfm

MUFFLER Idle dB WOT dB
DynoMax Super Turbo 89 123
DynoMax Race Magnum 94 133
Flowtech Afterburner 92 124
Hooker Competion 92 122
Hooker Super Competion 90 125
Summit Turbo 89 124
Summit Fully Welded 92 125
Thrush Boss Turbo 90 123
Thrush Magnum Glasspack 92 128

 

Thank you for all the info. I guess my next question is redundant. But what does everyone think of purple hornies then a few feet back to the end of the cab then out

 

I wonder why they didn't include Magnaflow in their test?

 

I run purple hornies on my 351C.....I have a buddy with them on a set of long tubes on his '72 f250 w/360, and it doesn't sound the best, but that could also be attributed to the exhaust leaks he has

 

Well yeah maybe it is my daily drive also.

 

351c revving w/purple hornie headers - YouTube

Here's a video of my 351C with the purple hornies. Remember, it's not an FE, so I doubt it'll sound remotely like this, and my phone doesn't do it justice. The mufflers dampen the sound a touch, until you open that throttle up, and then it's substantially louder than at idle

 

Oh yeah that's a ticket for sure I guess ill run the flowtechs just to please the 5-0

 

These are 3" Magnaflows, run all the way out the rear. Not loud until you mash on it and even then not as loud as Flowmasters or glasspacks.
Burnout - YouTube

 

Ooh that sounds good. If I put glasspacks it will be alil louder?

 

I had Hooker Aero Chambers on my FE. Took them off and put on a pair of 30" glass packs and the feel of the pants is much better. Sound is about the same. I'd be curious to hear what a pair of Spintech's sounds like.

 

That's how I am with smittys