How legit are "high flow" mufflers?

[Psychobroker]

How legit are "high flow" (aka fartcan, IMHO) mufflers? Here's one from eBayTaken from the auction description:"100% Brand New with Removable Silencer Made of Real T-304 Stainless Steel with High Gloss Polish Finish Ultra Fast Air-Flow & Light Weight Design Increase 12+ Horsepower (*cough* bulls**t *cough*)INLET 2.50" - 4" TIP - 18.5"L X 5"W X 5"H UNIVERSAL MUFFLER WILL FIT THE TITLE CAR AND MOST IMPORT AND DOMESTIC CARS THAT USES A STRAIGHT EXIT MUFFLER"Positive Feedback he's received:" dan_nguy( 3 ) Oct-10-03 00:53:35 PDT 2435283432 S Praise : Fast shipping, Great EXHAUST, Good price. I will buy from you guys again.""accordinglynice( 1 ) Oct-09-03 22:15:31 PDT 2434202601 S Praise : excellent cant complain ""03turbobug( 0 ) Oct-08-03 19:14:26 PDT 2434450112 S Praise : Awsome service very fast and a great product. Will use again""autotechs-com( 270) Oct-07-03 11:55:55 PDT 2434675530 S Praise : Fast shipping, Awesome muffler, very pleased! Would buy from again."and the list goes on and on...So, what do you guys think?

[DopeVibeGT]

Depends on what sound ya want from your Vibe. Want the usual rice sound that sounds like a weedwacker, sure. As for performance, to get anything, you should get one of the better cat backs, IMHO. As for 12HP, I doubt it.

[dmitri]

id get it and take out the resonator do custom piping...its cheaper and sounds good.No, it wont sound like a fart can because we dont have a honda engine, our engine is different and wotn sound buzzy. (well at least the GT)

[Psychobroker]

I plan on intalling a cat-back system down the road, but I was just wondering about the performance validity of these mufflers. Sound aside, do they actually increase performance?

[drunkenmaxx]

someone please answer this man's question, i would love to know the same thing since i am now officially broke and no catback is available for me anyway.

[MadBill]

There have been previous discussions on the forum re the power gain for a performance muffler and the need for a certain amount of exhaust back pressure to maintain low RPM torque, but in all my years of experimenting I have never seen such a need. Regardless of this, the reduced backpressure of a high performance system will increase power, but no one seems to have posted actual results. I built a dump/cut out/dual exhaust for my base Vibe that taps in just upstream of the main muffler (recall that there is also a resonator and two catalytic converters in the system) and the back pressure at 6,400 RPM dropped from ~4.5 psi to 2.2. As the system appears to be the same on a GT, the added exhaust gas flow for the 180 HP engine would likely give ~6 psi or more. My best guess is that a good muffler would add ~ 3-4 HP on a base Vibe and ~ 6 on a GT.Someday, someone will post good dyno data....

[dmitri]

a muffler is a muffler. if you get that, you wotn need a catback system (the only cat back out right now is magnaflow anyway)

[drunkenmaxx]

there are many catbacks! i'm thinking that if they would ever make a catback for the awd, the gain could be considerable, since the exaust is the reason for the loss of hp compared to the base

[badmojo]

Here's the best explanation of backpressure vs exhaust velocity I have found:http://mtcforum.zeroforum.com/zerothread?id=750

[dmitri]

none of them are true catback except for the magnaflow. all the other ones utilize the flange next to the rear axel. soon im going to get my N1 style muffler and gonna get custom piping done to it.

[Psychobroker]

What about the Borla system sold at ptuning?