Am considering this exhaust...1st attempt by anyone?

[USAF]

I like the sound of my 2ndary cats/h-pipe/resonator removal but am considering this configuration for better exhaust flow/HP;

Replace my current X-pipe with this "X-Pipe muffler" from Dynomax # 15553 ($110)

Dynomax Performance Exhaust | Mufflers | Ultra Flo X Mufflers

And remove the stock mufflers and run straight pipe instead of the mufflers. I know it will flow much better and will delete another 25 pounds or more. I have seen mention here of an exhaust that may flow too freely losing HP but would like to hear from someone that has proven this with dyno testing. Someone had talked of the exhaust being too free thus not allowing the primary CATS to fully do their job because the flow is too fast? I am retaining the primary CATS.
Thanks for any insight.

[tmiked]

Interesting. let us know !

[Weasel]

+1 Interesting...let us know.

[USAF]

The below statement comes from Dinan at this link:

Dinan BMW - Dinan's M3 E46 Exhaust

"I’m fairly certain that many of you have been exposed to a “bench racing legend” that would have you believe that increased backpressure will improve low rpm power and that low backpressure will increase high rpm output. Nothing could be further from the truth. An exhaust system is sized for maximum flow at wide-open-throttle and peak rpm. All exhaust systems are “oversized” for lower engine speeds (rpm), as backpressure is so insignificant that it can’t even be measured. Less back-pressure always results in more power at higher rpm, with no negative effect on lower engine speed performance. The amount of power that can be extracted from an engine at a given rpm as a result of exhaust design is really limited by the exhaust manifold or header. After the header, less backpressure is always better."

I have now ordered the Dynomax X-Pipe muffler and have scheduled a dyno session on a Dynojet. I'll do a before & after session with this concept. I am hoping I can show an increase in performance to show that I don't need to spend 3K + for an exhaust system that gives me more power. Maybe I'll market this system providing a direct bolt-on system from the flanges just after the primary CATS through the exhaust tips...

Stay tuned!

[Mark Ducati]

I too am looking for an affordable muffler to replace the stock ones... I'm thinking of some Magnaflows....

With the above mufflers, do you need to have some tips installed on them too... or is that all that you plan to install, just those mufflers?

[USAF]

Originally Posted by Mark Ducati

I too am looking for an affordable muffler to replace the stock ones... I'm thinking of some Magnaflows....

With the above mufflers, do you need to have some tips installed on them too... or is that all that you plan to install, just those mufflers?

My plan is to install one of the pictured mufflers where I cut off the secondary cats and then continue with the dual 2.5" pipes through to double tips where the stock mufflers now are. I want to do a before & after dyno test and tried to dyno my car this past weekend and could not. Couldn't fully disengage my traction control but am getting the updated software installed later this week so I can then dyno.

[Nepok]

I dont understand how flowing too freely could cause HP loss. Is it counter productive at one point?

[USAF]

Originally Posted by Nepok

I dont understand how flowing too freely could cause HP loss. Is it counter productive at one point?

The only reason I could see that there would be a horsepower loss is if the computer couldn't compensate for the free flowing exhaust somehow. A free flowing exhaust system should require a different air to fuel ratio vs. a restrictive exhaust but the computer should be able to adjust. I am going to retain the primary cats so there will still be the restriction involved with those.

On my 67 Chevelle SS, carb jetting adjustments are required depending on many aspects including header primary tube length, collector size, & overall exhaust system restriction. Exhaust design changes will almost certainly require adjustment by the computer but it should be able to compensate hopefully. I'll know based on the before & after dyno pulls.

[Bford100]

I have Magnaflows installed, everything else upstream from them is stock. Thinking of removing resonator too at some point.

[Bford100]

Mark, got your PM but I can't reply to you as I do not have enough posts!!!!!

You can e-mail me at bford100@aol.com

Thanks

Brad