Thread: Re-wirting engine management 99 disco 3.9.

Cats are normally up close to the motor. I'd guess your system in the "com mo doh" was twin cat, twin front mufflers merging after the diff into a single tip...well that's the way most holden V8 systems are made up. There are a few twin all the way but the norm is twin... twin... single. Trying to remember what the LR system is..... think it's twin then merges before or into the front muffler to single. An increase in size would help top end power and better efficiency.

I noticed when I made up Hellspawns exhaust the mufflers run very hot and the hotter they get the quieter the note becomes especially galloping down the freeway.

All the balance pipe would do is take out the pulsing which defeats the purpose (to me) of bolting on headers. That pulse encourages cylinder scavaging, the less pressure available the more ineffecient the cycle becomes and so long as everything else is equal, pipe size, length then just something else to get hooked around a stick. Balance pipes to me have their place however food for thought how many many older cars get around with twin (or more) carby setups with balance pipes between the intakes :?: [img]style_emoticons/<#EMO_DIR#>/biggrin.gif[/img]

the purpose of the balance pipe is to equalise the static pressure of both pipes cos they can be unequal length. It smooths over the exhaust note as well making it sound more refinded, rather than like a 30yo kingswood.


Looking underneath the LR, it would be best to merge the 2 pipes into 1 (say a single 2.5") then the intermediate muffler, and finally to a rear resinatior. Ideally the mufflers would be made out of stainless steel to give that crisp note. [img]style_emoticons/<#EMO_DIR#>/biggrin.gif[/img]