I'm sure this has been addressed in one way or another, but I'm not finding it easily.

The Walker 54488 Front Pipe from local parts store for 91-95 4.0 has inlet size of 2 5/8'ths and outlet of 2 1/4 total of 40 1/4" long

The Walker 55277 Front Pipe from local parts store for 96 - the late 90's has an inlet size of 2 3/4 and outlet of 2 1/2 total of 38 1/4" long

And otherwise pretty similar.

My '90 from the cat back is 2 1/2" and I plan to drop the cat and run just a glass pack.
.........so looking for manifold back higher flow.

When I get the ported head with LS1 valves, I'll grab a better header and probably the 99-01 intake manifold and 63 mm TB
but the long pipe header I'm looking at has a 2 1/4 collector...

So my question is this, the stock exhaust man has a 2 1/4 (+/-) collector.
How much larger can the intake pipe be over the manifold's outlet?

As it is, the stock front pipe is 3/8" larger than the stock collector...
Right?