there seems to be hundreds of companies offering replacement exhaust systems for defenders, does any body reccomend any specific makes and models, also what gain is there from fitting a dec cat pipe as opposed to an entire exhaust system. do de cats work?
any help with this topic would be grrrreat!
Personally I see little point in a de-cat, I certainly wouldn't worry about who'd it was. It's a bit of friggin exhaust tubing nothing more. So as long as it fits, they'll all do 100% exactly the same thing.
In terms of decating, yes you can potentially gain a bit of performance, but you'll fail an MoT or road side emissions test. For the limited gain I can't really see the point of the hassle of fitting it and removing it, even if it is once a year.
Plenty of other ways to improve performance which you won't have to remove for an MoT.
As for the rest of the system - that's the key word
"system".
An exhaust is exactly that, so you need to look at it and treat it as a whole.
But it really depends what you are wanting to achieve. A bigger down pipe, high flow cat (or decat), plus a free flowing exhaust and low resistance silencers will make it louder (which some like, some don't) and will improve the engines breathing, so make it a little ore free reving and release some power, especially in the higher rpms.
But it's a compound affect, improve the exhaust, improve the induction, alter the turbo map and the fuelling map and it'll really fly.