Does anyone know the cheapest place for exhaust components?

My first stab at an exhaust is reeeeeally loud, so i want to modify it once through the MOT (yes its an understanding MOT tester).

I'm specifically after something like This but cheaper!

Any help appreciated.

Thanks.

Still needed.

I'm thinking about making my own box, so anyone with some spare 2" perforated tube or a 180 degree bend would be appreciated.

Cheers.