There is no technical reason two well-made parts from different manufacturers cannot work together. The reason it sometimes fails is entirely mechanical, and it comes down to three measurements.
Nominal pipe sizes are nominal. A 3.0 inch pipe from one supplier and a 3.0 inch pipe from another can differ enough that a slip joint is loose on one side and will not enter on the other. Measure the outside diameter of the pipe you need to meet, not the advertised size.
A two-bolt flange and a V-band do not meet. Two two-bolt flanges will only meet if the bolt pattern, the bolt circle and the plane of the flange all agree. That last one - the angle - is where most mismatches live, because exhaust sections are rarely perfectly perpendicular to the pipe axis.
Even where the geometry agrees, the support points may not. A hanger in the wrong place leaves the joint carrying load it was never designed for, and that is how cracks start.
There are three legitimate answers. An adapter section, if the diameter and the flange types can be bridged safely. A different variant of the part, if one exists for your configuration. Or a short custom section made to join the two. What is not a legitimate answer is forcing a joint that does not want to close - that is how you get a leak you will chase for months.
Send photos of the joint you need to meet, the measured outside diameter, the flange type and where the clamp sits. A rubbing or a cardboard template of the flange is even better. We will confirm whether a stock part suits or whether it needs to be made - see Customization if it has to be a one-off.
