Upgrade deciphering

Assume nothing. Ask someone that has his product.
What did you find on the chip?
I actually just got the car back. Had to put a new radiator in it. I went with the 3" welded dual fan set up from GN1. So I haven't had much time to mess with it. I am also thinking the 3.42 gears were removed for one in the 3.73 range. My speedo is about 8 mph off. And I want to switch back so I need to check that also. Any idea if I need new gears who is a quality vendor? I don't want some foreign aftermarket sweat shop Chinese garbage.
You state you are running 275/60/15s. They are 2" larger diameter than stock. That is why your speedo is off. There are speedo gears for the trans that would correct the accuracy but they are nearly impossible to find.
If you want to check your ratio, a simple test is jack the rear of the car off the ground, put it in neutral. Put a mark on the rear housing and yoke. Spin a tire by hand and see how many times the driveshaft spins for one rotation. That will also tell you if you have a posi or if it does and it's dead. Both tires should spin in the same direction.
It has posi. And it works fine. I think the rear end is not a 3.42 gear anymore. I think its around a 3.73 +- . Question....wot I do not get to full boost say even 15 psi before I come damn close to redline. Would this be another sign its a different gear? I would assume rpms would follow or equal boost? The car wants to keep pulling but I run out of rpm. It flys thru the rpm range. Its effortless power but if I'm leaving something on the table I want to get it back. Unfortunately in Peoria, Il there are not many knowledgeable people to get with.
It is 10 mph off with the stock wheels and tires. The 275/60 are the drag slicks it came with. I am now on 275/40/18 and its about 8-9 mph off.
I'm also running 112 octane gas till I get a new chip. Its the highest pump gas here and buying by the gallon from a race shop is even more expensive lol.
If it's leaded, your o2 sensor will die in short order.