So I'm trying to save some money and Im thinking about upgrades for my 89 T2. I hear the best place to start is with the exhaust. I was looking at down pipes the other night and saw a few that peak my interest. Cork sports has an 80mm 304 stainless steel pipe for about $170 and apexi has a 70mm 304 stainless steel for almost twice the price. Also mazda trix has one from Racing Beat that is also stailess 3". Im not sure if that is bigger than the other two. Im terible at that kind of math. So what would be the difference between the three besides price? Do I need to upgrade fuel management for this kind of upgrade? I figured I would get your opinion on where I would get the most for performance for my money.

 

80mm ~ 3.15"
70mm ~ 2.75"
3" ~ 76.2mm

 

Haha thanks for the math. So how about the rest of my question? Would there be a big difference in boost levels between the three pipes?