Extreme X-pipe, but sound is not shocking

Trial and error, pretty much, unless you want to spring for Fabio's exhaust. Late 575Ms came with straight pipes, which give the most hp and torque, but can resonate with some mufflers.

 

My 456 now has stock cats, tubi back boxes, and Braden straight pipes in place of the stock resonator. It sounds good, although drones a little at certain revs

 

I was wondering the same thing. Now that I have the straight pipes I could bridge them with a tiny crossover to see if that handles the drone waves.

 

I want to try cat deletes and still use my OEM center and the Fuchs straight through rear mufflers. The trick to get good sound is to hear all the twelve cylinders coming through the tail pipe but with some muffler so it is decent sound level.

 

Making the exhaust an equal length between the manifolds (unequal length from the factory) and an X pipe really cleans up the sound. I've been around a lot of different 550/575 and my car is the only one without the exhaust chop - especially at idle. I have no mufflers (and larger diameter exhaust) and my car is quieter - with valves closed - than other cars with center muffler delete & aftermarket rear mufflers. I have zero drone at highway speeds - cannot even hear the exhaust unless I get on throttle. To make equal length you have to get creative with the space available.

 

With that said... having an X or H does seem to help greatly according to multiple threads on the subject.

I like that the merge pipe going to a larger diameter, but it still necks down compared to the factory 2.25" exhaust diameters (even the crushed 2" sections exiting the center muffler). You're likely losing power in the upper rpm, but gaining torque in the low rpm. It seems the H-pipe or a true X with larger diameter piping would net you more power and the merge to balance the sound. If there is room to run a second set of pipes around your merge, like this |X| , it might sound good and not have a restriction on flow

 

I know the 575 is unequal from factory, were the 550 headers equal?

 

550 is unequal also, the exhaust leaving the front manifolds has a longer distance to travel than the rear.

 

The other option is to make the pipes the same length at the headers, which is what Fabio does. Sound pretty good, too.

 

In theory X should be better than H because of the shape. Idea on why is that exhaust pulses coming out from different cylinders follow each other into X and first one into it pulls second one from other side emptying cylinders better on exhaust cycle. First and second meaning two cylinders at opposite side of engine V that ignite after each other, not cylinders number one and two. That is at least theory and based on some V8 applications it works with both unequal and equal length headers.

 

In actual fact empirical results have shown the X pipe causes interference between the pulses instead of boosting extraction. Straight pipes produce more hp and more torque. The reason for X pipes and H pipes is to reduce resonance and some owners like the exhaust note better, even at a very slight loss of performance.

When Ferrari went to straight pipes on the 575M in late Summer 2003, they had to fit a new set of mufflers to deal with resonance.