Fitting a new section into an existing system is not guesswork, and it is not a question of brand loyalty. It is four measurements and one photograph. Get those right and the answer is usually straightforward.
The outside diameter of the pipe you need to meet. The distance from the joint to the nearest support point. The angle of the joint relative to the pipe axis. And the clearance available around the joint, because a thicker pipe needs more room than the factory part did.
The joint itself, framed so that both the flange or slip fit and the surrounding structure are visible. A second photo showing where the pipe runs relative to the subframe or the fuel tank tells us about clearance that a close-up cannot.
If you are joining at a flange, a rubbing or a cardboard template of the bolt pattern is more accurate than any measurement taken with a tape. Trace the flange, mark the bolt holes, and send it with the photos. It removes the single most common source of error.
A section that joins perfectly can still foul something. Before you order, look along the path the new part will take and note anything within a few centimetres of it: heat shielding, wiring looms, brake lines, subframe braces, the fuel tank. Tell us what is close and roughly how close, and we will tell you whether the section you are considering will clear it.
Sometimes an existing catalogue part suits, and sometimes the joint is unusual enough that the answer is a one-off. Both are legitimate outcomes. Send the measurements and we will tell you which one applies to your car rather than leaving you to guess - see Customization if it has to be made to fit.
