Yeah that sounds about right. One thing you can do is 2" upto the muffler and a 2.25" tail pipe out of the muffler. That set up seems to work fairly well with a stock head, you increase throttle response keep bottom end and still gives you more top end.

The girl friend has stock manifold/ collector/ 2"pipe/ removed cat/ turbo muffler/ full tailpipe. All pipe on that is 2"from the collector back and her little motor has some pretty good go go, it will cruze at 85 down I-5 with quarter throttle in fifth turning 33's and 4.88 gears, also it is a 86 22re sr5 x-cab.

Either way increases flow which is what free's up pony's. However 2.25" is the biggest pipe that is effective, you do not want to go any bigger.

I bet that once you put the new exhaust o-ring donuts( they cost like a buck) on the collector it will fit nice and tight.