What is a good singe in/dual out bolt on system that sounds good, BUT, isnt overly agressive and minimal droan, preferably none. Magnaflow???

 

From what I understand, the Magnaflow and the Roush Street Legal kits are amongst the best cat backs for daily driver duty that won't buzz your ears off on those long family trips.

 

Awesome, like the kit they have on Jegs??

 

i went to my local muffler shop (muffler man) and told them i wanted a cat-back dual exhaust on my 04 5.4 screw. its loud enough it can rattle the house when i start it but its not too loud. its just right.. for $315 installed with chrome tips

 

yep, 2 best kits on the market for tones and lack of drone...I prefer the Magnaflow myself.

the Roush Offroad is pretty beefy on the tones though. A bit expensive, but it's quality stuff

 

I've actually found the Roush kits to be anywhere from $75-$100 cheaper than the equivalent Magnaflow system.

 

yeah, they are all expensive. My magnaflow kit cost me $479 back in 2006. I still think it was money well spent.

but next time I will simply buy the muffler only and have my local shop weld up some new pipe and some nice tips. I think I can get the same results for 1/2 the price.

 

I don't doubt it. Still though, there's its nice to know a healthy exhaust tone is all of about half an hours work away and able to be done right in your own driveway with the bolt on kit.

I'm still having a tough time deciding which kit (Magnaflow or Roush) to go with personally?

 

I have listed here a muffler shootout test done by CAR CRAFT:

MUFFLER FLOW TEST

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

DYNO TEST
All mufflers were dyno-tested on a 355-cube SBC with 10.0:1 compression, Air Flow Research 190 aluminum heads, a CompCams 292 hyd. a Victor Jr. intake, a Holley 750-cfm double-pumper, and 1 5/8 Headman headers.


MUFFLER HP TORQUE 2,500-6,000rpmAverage
Hooker Competition 397.4 381.1 286.8hp/351.9 lb-ft
Thrush Boss Turbo 407.1 384.9 292.1 hp/357.5 lb-ft
DynoMax Race Magnum 409.5 394.3 298.8 hp/366.9 lb-ft
Flowtech Afterburner 409.7 391.2 294.8 hp/361.7 lb-ft
Thrush Glasspack 409.5 389.8 297.7 hp/365.3 lb-ft
Summit Turbo 411.5 386.3 291.5 hp/357.4 lb-ft
DynoMax Super Turbo 412.7 387.2 292.6 hp/358.6 lb-ft
Hooker Super Comp 413.8 387.2 292.8 hp/359.0 lb-ft
Summit Fully Welded 415.4 390.7 295.6 hp/362.4 lb-ft

While there are mufflers that will out flow a glass pack design, it also depends on the design. Does the glasspack use "louvers or perforations" - Louvers reduce the flow by as much as 50% but Allied resonators (that sell for $20-$40) each and available at any muffler shop) installed backwards in independent test flowed 90%+ of a "race spec muffler". Others using other brands consistantly showed similar results.

 

Nice....but neither the Magnaflow, or the Roush (Borla) mufflers in the kits I'm considering were present in that test?

 

Broader perfoamnce did a flow test a few years ago, and the Borla w/ 2 1/2" inlet/outlet had a flow rating of 373 cfm. Magnaflow (race/bullet style) & Hooker will flow identical- the Hooker Max Flow flowed 521 cfm w/ 2 1/2" inlet/outlet. The Hooker Aerochamber flowed 324 cfm. By comparison, a straight 2 1/2" pipe with no muffler flowed 521- so their is no restriction with the straight through design units.

 

I guess the real question to ask, would be at what point does all of that CFM become necessary and what point is it a hindrance? Mufflers sporting ultra low restriction and high flow figures are impressive on paper, but if you engine is unable to utilize their capabilities, is one system really going to be of much greater benefit than the other? I’d be more interested in holding onto the most off idle and low RPM torque I could with a system that still retained some remnants of back pressure than I would the additional 2-5hp gain I pick up only on the top end with an exhaust system that all but cuts it completely and sacrifices power in the lower ranges to do so.

Let’s be honest...most of us change our exhaust systems for a more aggressive "sound" more than anything else. I don't think there's one person here who could honestly claim they picked up any real performance from installing an aftermarket cat back, or mufflers in place of their stockers on a stock truck...or even one with moderate performance bolt ons.

 

the more cfm flow, the less restriction, the less restriction, more "true" sound, less throttle required to accel or maintain speed. The issue of backpressure, well, if you have an engine that turns 7,000+ rpm (such as the euro's do), it is an issue they experimented with back in the late 80's/early 90's, where BMW's MB's, etc had a exhaust vale that at low rpm stayed close, directing exhaust gases through a single taio tip, and at about 3500+ rpm, opened allowing gases to exit though 2 tailpipes,- theor resonaing was the backpressure gave them increased torque at lower levels. Now I do not doubt their tech, but, our engines operate under a complete different set of parameters. I don't think the Euro's even use that tech anymore- as when you reduce the backpressure, it is a simple as the ECM adjusting the fuel mixture. Those who have experienced "lag' for lack of a better term, 9 out 10 it is related to an aftermarket "cold air intake unit" where the intake sensor is relocated to a position that is not condusive to ensuring the ECM's ability to provide the proper A/F mixture at low RPMs. The remaining 10%, usually related to the ECM not having enough time/miles to adjust.

Think of it this way, all those pre-1974 vehicles (non-cat), that even had the exhaust systems completely cut off, running at the track with open headers (no longer allowed), certainly didn't suffer from lack of back pressure to run 100 mph 1/4 miles. No matter if you even run stright pipes off the cat, the cat will still provide some backpressure so the issue is then why the flow test...

1. many mfg's had some really wild claims!
2. many mfg's claimed others products were no good and flowed very low
3. The test by car Craft & broader re-affirmed that which all the old hot rodders knoew for many, many years....then it was re-afirmed by bench flow testing.

Hooker & mangnaflow even have minimum exhaust pipe recommendations based upon engine CID and HP. Then you really know in terms of size, what is really needed and what is for "looks". For our 5.4 (330 cid), 2- 2 1/2 pipes are more than adequate, a single 3" is equally as good IIRR- so when you see 2- 3" pipes with 4' tips, it's just for looks!

 

+1

I was so close to buying a pre-made setup but read through a few threads on here and talked myself out of it. Also I have a very wide trailer hitch that wouldn't allow the pre-made kits to fit.

You can get a good deal on a Magnaflow muffler either di/do or si/do, on eBay for $100-120. Then tips for $30ish and have the shop run everything for roughly $200. Total cost for me was $350 for the whole setup. A kit from Magnaflow runs $700+.

As for removing the cats that's just all around bad news bears.