Can someone explain...

[ivawart]

...what's the benefit of having a 4-2-1 manifold over the stock setup?

would also like to understand why people change the 1st/2nd decats. Does it improve performance, or is it soley for the type of sound that the exhaust makes?

These probably seem like daft questions for someone whose been a member of this site for a while, but until now I've focused on getting the look of my k11 just the way I want it (its taken some time, and if I'm honest, will probably still need tweaking in the future), and now I'm moving onto getting the mechanics upgraded. Virtually know nothing about it, and am planning on learning as I go. You'll probably find posts from me on here from time to time asking further daft questions lol.

 

[frank]

extractor exhaust manifolds have been around for about 100 yrs, and a google on "decat" brought up 60 million hits

 

[superls]

simple answer, the mods you have mentioned help the engine breath better

 

[ivawart]

Been reading up on it and think I'm getting the gist of it. One thing that keeps popping up is that removing the decat can void an MOT on emissions. Is this an issue on newer cars or all cars? Or is it not an issue at all? I'm only asking here because I can't find a conclusive answer via google. Some people say yes while others say no.

 

[karlj]

Been reading up on it and think I'm getting the gist of it. One thing that keeps popping up is that removing the decat can void an MOT on emissions. Is this an issue on newer cars or all cars? Or is it not an issue at all? I'm only asking here because I can't find a conclusive answer via google. Some people say yes while others say no.

Depends which cat, the k11 will pass an mot without the second cat but you'll need the first cat

 

[ivawart]

Depends which cat, the k11 will pass an mot without the second cat but you'll need the first cat

so what about the people on here that have both cats removed? Are they not failing MOTs?

just asking, not doubting what you're saying

 

[karlj]

More than likely swapping for a good cat or going to a friendly mot'er

 

[ivawart]

ah, ok. hmm, maybe i'll just try with removing the second cat for now

 

[mottymicra]

It takes about an hour to change over the 2 cats, once a year it's worthwhile in my opinion, easy way of getting horsepower

 

[superls]

it depends how 'friendly' your mot man is

 

[ivawart]

it depends how 'friendly' your mot man is

Er ... I wouldn't let him cop a feel, if that's what you mean just kidding, might have to ask my regular MOT guy if he'd be willing to look the other way