Exhaust questions

[rcx106]

I'm thinking of making up my own exhaust because the standard exhaust on my 4x4 (Vitara) is heavy, bulky, obtrusive, and knocks around when off roading. Plus I like a little bit of exhaust noise, helps feel what the engine is doing.

I've never done exhaust work before, apart from welding in new sections to pass an MOT. Questions:

I've measured the outside diameter which is 48mm at the cat, and then 43mm outer diameter at the rear section (there's only two sections). What do these sizes equate to in nominal exhaust size? Online shops list 1.75", 2", 2.5".... I am planning on running the same diameter all the way through on the new one.

The section with the cat joins to the rear section using a flange. What are these flanges called so I can Google and buy?

Are there any glasspack silencers which are road legal? Not sure about cars, I ride motorbikes and on bikes they need to be E marked. On bikes it's possible to buy an E marked silencer with a removable inner baffle, so you get a straight through exhaust and still have the E mark.

Just to check the obvious, the longer the silencer the better it silences right? I see universal one in 12" and 18". I have space for upto 21".

Any tips for which silencer to use if I just want a bit of exhaust noise? Remember the main aim here is to have a light and unobtrusive exhaust. I don't want to be too antisocial. And remember that my car only has ONE silencer.

Thanks!

[rcx106]

Aha, it's the internal diameter we go by. I've checked an online exhaust calculator which says I only need 1.7" pipe. I will go with 2" as it's a standard size and it's the closest to the pipe size at the manifold and cat.

Just dawned on me that if I'm making my own exhaust then I don't need to use OEM type flanges. I can use whatever joint method I fancy! What's the best or most convinient type of joint? Simple clamp type?

[rcx106]

Just read topics on law on exhaust noise. So I need to keep noise to be comparable with the original system. I'm not a by-the-book person, so a system that gives moderate noise would be fine by me.