As educationally spammy the post is, there isn't a drone. The noise is 264 hz, related to pipe resonance AFTER the downpipes and only happening when the engine is under load and in a specific RPM range. As the exhaust temps get warmer, the noise isn't as bad (but still bad) and I helped with this a bit by using a thermal wrap on the factory H pipe, making the air get warmer, faster. The factory H pipe is causing it due to the bridge being tuned for those factory cats and not straight through. The ultimate solution (which is gonna blow some minds in this thread) is an X pipe. I've been in talks with an auto parts (including exhaust) manufacturer about making my design as I do not have a mandrel bender to do it myself. The bonus to them making it is they have the jigs made to make a production run of them, making my exhaust available to the masses.I hope this helps and sheds some light on Mclaren sound, quality sports car sound.
EMF Audio- I like your handle. The following might alleviate the resonance and drone factor of the catbypass pipes you received or any catbypass pipes from any company. All McLaren catbypass pipes must be wrapped or covered to greatly reduce sympathetic resonance also called droning. Droning noise is a lousy obnoxious noise that causes bad sound in the cars cabin. Most companies try to eliminate the noise through engineering.
If your mclaren pipes are loud wrap them with materials that will absorb alot of the drone and subsonic noise. OEM Mclaren metal heat shields do a really poor job of absorbing sympathetic harmonic frequencies as these were designed for 4 restrictive OEM 600 small catalytic converters. Aftermarket HJS German highflow catalytic converters or catbypass pipes will obviously free up exhaust flow and velocity and the factory Mclaren heat shields will allow vibration and subsonic noise to radiate into the cockpit. This is inevitable.
A solution for any brand of sport cat or catbypass pipes for Mclaren cars like the MP4/650/570 would be Fabspeed MIL spec thermal blankets made of 321 stainless steel 2000 degree cermaic matting 25mm thick and wrapped with rock wool outside covers and 321 stainless steel springs. The Fabspeed Mclaren thermal blankets can easily be retrofitted to stock or aftermarket Mclaren sport cats or catbypass pipes. Simply remove or bend down the mounting tabs.
On other datapoint. Fabspeed Mclaren systems are 100% designed and made inhouse from T304L , 321SS stainless steel with MilSpec defense quality blankets that are state of the art.
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Here a picture of our system and blankets. Investment casting inlet bells for absolute maximum flow and investment cast outlet elbow for maximum flow.
Hope this helped and we can quiet or update any system. Cruise over and try out a McLaren at Fabspeed Motorsport USA.
joe Fabiani Fabspeed Motorsport USA