Originally Posted by F.I. Inc.

A very valid question!

The reason why most manufacturers use flex joints is to account for inconsistency in their production pieces. Ex: Nissan makes thousands of 370's in one year. The quality assurance on the exhaust system is probably fair at best and the flex joints allow for slight alignment variance.

We have never used flex joints in our production cat back exhaust systems for a number of reasons. Stainless Steel expands when it gets hot and flex joints will add to it like an accordion. They hinder performance by creating turbulence to the exhaust flow from the inside. They allow the system to sag as well.

We have prototyped all of our exhaust systems correctly from day 1 and do not have fitment issues. Our quality assurance is top notch and second to none. I stand behind that until the day I die! Now in some cases we use flex joints. On some of our turbocharged down pipe applications we use them. We judge each case based upon it's circumstances.

The exhaust system is bolted to the manifolds. Then it is hung in rubber. The rubber is to allow movement as to when the engine torques. See the engine is sitting in rubber motor mounts so when it torques everything bolted to it Will want to move with it. If we solid mounted an exhaust to the frame it would break when the engine torqued.

Here is some food for thought,

This is not our first car. We have over 10 high end cars that we currently have a production exhaust system for. Not one uses flex joints in the cat back. Cracking is not an issue that is common with our products especially our cat back's.

If anyone is deeply concerned about the lack of flex joints and feels they want them, We have a mandrel bender in house, we are they designers and producers of all of our products so we can fulfill any request. If you want the flex joints I will install them at an extra fee to make you feel more comfortable. I am not being sarcastic I am being serious! But, in my honest opinion they are not needed.

I will say once again, it is a valid question...

Thank you, Tony
(818) 882-2788