Mac 2-1 Aftermarket Exhaust for a 80 KZ440 rejet?

So I bought this kz440 about a year ago. I've been slowly modifying it ever since, but one of my sticking points right now is this exhaust system I bought for it. I have 2 shops in the greater Seattle area telling me 2 different things. One says I won't need a rejet, just a tune up. The other, a licensed Kawasaki dealer ( and the more expensive option), says I will probably need one. I think the stock jets on the KZ440 is a 92, nd the original exhaust is a double walled 2-2. the Mac that I bought is a single walled 2-1.

So my question is, does anybody have any experience or knowledge that can help me figure this out? You guys are the gurus, and some of the dudes I've talked to at shops have never seen a KZ in their lives.

P.S. I have the stock airbox.

I have a MAC 2-1 on a 750 twin and it does not require rejetting using stock muffler. I doubt yours will either. You might get it to run a shade better going up one jet size... or, maybe not but I think it will run pretty good with stock jets.

So I looked at the stuff the previous owner gave me, and I was wrong. the jets he has in there are 41 for the pilot and 65 for the mains, and 120 for the main air jets. The stock mufflers are no good anymore, they rusted out. And I don't think they would fit the 2-1 pipes either since the stock is 2into2.

MAC pipes for the twins are made to run good with stock jets. Their airflow is pretty much similar to stock. I would try stock jets for starter and see how it runs. At most, you might go up one size on the main and pilot but you may not need to. On my 750 twin, I tried a larger main jet and it did not run better. Go to the kawi explosion drawings and find out what jets were stock size. make sure it's the Canada model, some of the US models had very lean jets (like California) and you definitely don't want those.