Sorry, just reposting this from the RR section in order to open it up to you Disco owners and other V8 experts..

Does the ECU take back pressure in the exhaust in to consideration somehow? This is what a friend told me. I was planning to de-cat and I also need a new back box as I just discovered today. I can't simply go out and buy one, will have to get one hand made. I know a guy who knows a guy who does just that. He's great at tuning them for sound too but I doubt he's thought about how much pressure or resistance there should be - if at all.

My friend however tells me if I do this I will have running problems, esp if not enough back pressure! So how do people off-road these V8s then? Don't some just bin the silencers and cats entirely? How do they (you) run?

As I understand it, The back pressure in the exhaust is created by the restrictions and baffles in the system used to reduce noise. (in a standard system) Therefore the ecu is mapped accordingly (at the factory) to run at its optimum taking this pressure into consideration.

Getting rid of this pressure, or some of it, is normally a good thing, and should cause no problems. In fact will benefit most engines, letting them breathe more easily.

Making changes to exhaust back pressure can only cause problems in 2 stroke engines, as far as I'm aware.

Hope this helps, Dave.

And No, the ECU has no way of measuring back pressure, Dave

All I needed to hear! Thanks Dave. And LMAO at your "location"!

Can you do a post once youve done it, as i want to decat my 4.6 hse, people say they run cooler and better.

will do. got some other more pressing problems now - the bugger has started cutting out, dropping revs and flat out not starting! all in the space of a couple of days!