Originally Posted by Built4Adrenalin

Honestly, truth be told...a test pipes a test pipe. As long as it is good quality steel, TIG welded and fit precise with good gaskets and a nice seal with factory O2 sensor ports the rest of the cost is all name! It's literally like 3 ft of pipe each with a 15 degree bend and a threaded hole with a mounting bracket at either end, those are the only 2 welds. If you get pipes without an o2 sensor corrector and it does trip the light, weaponR make 30-40 buck solution! Their own CEL corrector and clearer that doesn't interfere with any other code not pertaining to emissions. The resonator settles all of the wild combustion deposits and inconsistent exhaust emissions and smoothes them out into an even direct pressure toward the next stage of your exhaust. In other words, generally not as noticeable volume difference, but a noticeable tone difference and of course throttle response! I do not have the raspy or crackle tone as long as I start my car and let it idle 5-15 minutes depending on outside temp, but from cold start until operating temp 3-5000 RPM definitely some crackle....no big deal! Don't bust your wallet on killer big name irrelevant parts, save it for the technical complex parts that you just feel better about paying for the name to have the peace of mind that you bought an overpriced piece of excellent reliable technical equipment! Anyway, hope this opinionated rambling helps out!

Originally Posted by Hydrazine

In my days as a rocket scientist at Marquardt designing rocket engines for JPL there were many challenges in ensuring the performance and reliability of the rocket engines.

One of the greatest challenges was designing an injector that could produce smooth and stable combustion in the combustion chamber. There were occasionally these acoustic resonances (tangential modes) in the combustion chamber that could start a run away condition where it could quickly destroy the engine. To address this problem we used Helmholtz resonators inside the engine to damp out the tangential acoustic resonances. A tangential resonance was a shockwave that would spin like a tornado inside the combustion chamber at 20K Hz. Much like ping or detonation in a internal combustion engine, this tangential mode would scrub off the boundary layer and radically increase the heat transfer into the chamber walls and result in the engine overheating.

Helmholtz resonators were the solution to these tangential waves. By properly tuning the Helmholtz resonator to the frequency of the tangential mode you could either magnify or eliminate the destructive shockwave.

After studying the application of Helmholtz resonators in depth I began to see how they could be used in a range of applications other than rocket propulsion. Particularly in automotive. If you have studied header design it is clear their function is all about using exhaust acoustics to increase scavenging. ART pipes do the same thing but in a different way. Headers use 1/4 wave resonators to make power. ART pipes use Helmholtz resonators to make power.

Traditionally, if you already have an intake, headers, test pipes with a full catback exhaust and tune, that was the end of the line. There was no more left to gain. ...But not any more.

This is Motordyne's debut of the patent pending Advanced Resonance Tuning (TM).

The plot below is without exhaust cam phase tuning. The ART pipes respond very well to cam tuning.


Regular test pipes always result in a large loss of low end torque. Compared to test pipes, the ART pipes produce a large gain in low end torque that is clearly felt and can be very usable for auto-cross or powerful launches in drag racing.

Originally Posted by Golden_Armz

Just bought Megan racing resonated test pipes. $150. Like the person mentioned above, it's just test pipes. Not gonna spend 600 for test pipes for similar results. I can deal with a little bit of rasp... No big deal. Saved me almost 400 dollars.