Alright..see If I cant help some..
To test the Catalytic...get on an open road, and floor it...
if it seems to 'hit a wall' as in, it doesnt want to accelerate any more...bad cat...also if you smell a really nasty smell with heavy throttle, thats another sign. Or you can have a shop run a pressure test to see.
It would be a good idea to replace the front O2 sensor as well, along with new plugs, plug wires, fuel filter, oil change, trans fluid change and filter, and supercharger oil change.
15 in the city is a little low...should be 17-20ish with lots of stop and go. I get about 30-36 on the interstate, but thats with lots of flow mods...
On the highway, expect about 25ish with a good tune up.
As for the boost gauge. That's about right. On a stock car, you dont make much boost. WOT should read full bars..
Even at 1/2 throttle, I might see 1 bar, if that. You really have to get into it to be making lots of boost.
Also, be a good idea to replace both belts, Accessory and Supercharger, to be safe.
Good luck with the car, and any other problems, feel free to use the search feature, and if you dont find anything, either ask me, or the forums.
Welcome, and congrats on the car.
