X pipe price

[LostKiwi]

So what actually makes the increase in noise , obvs removing the cats will increase it a little but in the past when ive measured before/ after its only a decibel or 2 , how does crossing the exhaust gases make the car rumble more ??

It doesn't. If anything it makes them rumble less by removing some of energy that would have been sound and using it to produce torque and power.
It gives a different tone, smoother and less gutteral.

 

[bembo449]

Hmmm , ive got my X pipe but i reckon its not guna be so easy to fit , bare in mind a comment earlier on about it going into one then back to twin , looking again this morning there is a section that is pretty much as one so i would need to get round that somehow

 

[LostKiwi]

X pipes really only benefit systems that have separate pipes for each bank from end to end.
The purpose of them is to harness waste energy from the gases in one bank to help clear the gases from the manifold in the other bank.
The V8 rumble is a product of the firing order.
In typical V8 (that doesn't use a flat plane crankshaft) the firing order the firing pulses per bank are LRRLRLLR. It's the double pulses from each bank give the rumble. That double pulses contains a fair chunk of energy in the form of expelled gases. By directing those gases past the end of the pipe from the opposite bank they create a partial vacuum to help draw the gases out of that bank.
To get the best effect the angle of the junction should be as narrow as possible and the conjoined area should have a smaller cross section than the combined cross section of the two pipes from the banks. If the junction of the X is 90 degrees (as many are) the effect on the banks is reduced as the gases flowing past both pipes at 90 degrees created a partial vacuum in both, slowing gases that have already gone through the X pipe.
Hard to explain but hopefully you get the idea.
This is a bad one:

Gas flowing top left will mainly exit bottom right, creating partial vacuums in bottom left (desirable) and top right (undesirable).
This is better:

Internally there is an oval shaped gap in the pipes allowing some of the gas from top left to flow into both right hand pipes this giving a better vacuum in the bottom left pipe.

The length of the open conjoined area can also have an effect. In testing on Holden 5 Litre V8s they found 10" joined area have the best results. This is far longer than most off the shelf units.

 

[00slk]

My 55 had the sound of thunder, once rear de-cat, front sports cats and X-pipe fitted it sound is a muffled thunder sound.
Maybe a complete muffler removal

 

[robertquantrell]

My 55 had the sound of thunder, once rear de-cat, front sports cats and X-pipe fitted it sound is a muffled thunder sound.
Maybe a complete muffler removal

Bit of a thread revival here! @00slk What front sports cats did you install on your 55? I got some Magnum ones but a quick chat with EMP and they said they won’t fit as primaries? Thanks!

 

[00slk]

Bit of a thread revival here! @00slk What front sports cats did you install on your 55? I got some Magnum ones but a quick chat with EMP and they said they won’t fit as primaries? Thanks!

The ones I had fitted were from the USA, supplied and fitted by AMT Engineering near Beeston Norfolk. I know those type I had fitted are no longer available. They do supply an alternative but that's about all I can tell Robert sorry not any more help to you.