Exhaust

[Mike in Texas]

I'm ready to get an x pipe with cats for my 90, see sig for mods. Which one do you guys recommend, needs to have bung for o2 sensors. Also how about an estimate of the rwhp I should be getting before and after the exhaust change. The nearest dyno tune is 2 1/2 hours away and I'd like to have some idea of the power I should be making before I get the tune. Oh, I'm getting ~5 psi boost at 5000 rpm.