BBK 1 5/8 Full Length. Question about collector size?

[Brian992V]

I measured the collector on my headers and its a measly 2 1/4". I've opened it to 2 3/8 but I'm unsure on whether to open it to 2 1/2. Has anyone done this? I don't want to have issues with it leaking. I'm doing the same with my H pipe where it mounts to the cat back. It measured 2 1/4 as well.

 

[white 89 GT]

I have done that to two different sets, on my shorty`s I did not take it to 2.5 because it would have leaked, but on the long tubes the mid pipe comes straight into it so was able to get close to 2.5