Is this common? I jus got a hotshot header, catco high flow cat, cha chi mufflar, and custom 2.5" piping installed on my car along with a CAI. Would this be grounds for a CEL??? or is there another prob that came up at around the same time?? Think that resetting my ecu will fix it??

I think you can thank the CEL on the new high flow cat. I'm not sure if resetting the ECU will do anything.

MODS:

HRC 16g turbo kit, Spearco custom FMIC, Custom IC piping, VT rebuilt engine: Custom 8.8:1 compression CP pistons, Eagle connecting rods, Melling oil pump, Clevite bearings, 370cc injectors, Vortech S-FMU, Apexi N-1 catback exhaust, AFX UDP, Autometer boost gauge, fuel pressure gauge, EGT gauge, Corbin's digital A/F gauge, Tokico Blue shocks, Tein springs (1.5" drop), 18" Konig Verdicts rims, VIS stock-style Carbon fiber hood

yeah try resetting the ECU, but its prob the high flow cat, now the ECU thinks the Stock cat is less effecient and thinks its old/damaged.
If resetting the ECU doesnt work you can do this to get rid of the CEL http://www2.cesa12.k12.wi.us/brent/personal/neon/pic/cat_resistor.html

1998 dodge avenger 4 cyl AT
Mods are:
Not enough

It is my understanding that my car is OBD1 since it was made in July of 1994. If that is the case then wouldn't i technically be able to remove the exhaust completely after the o2 sensor with no probs? Just a thought, unless my car is actually OBD2...but like i said i thought that it was pre december of 94 were obd1

I jus did the key dance and got a code 12.

"direct power input to the PCM has been disconnected within the last 50 key-on cycles"

so that jus means that my ecu got reset a lil while ago right?? In which case me is good

Yep.. Once the code comes back do the key dance again to be sure. I am willing to bet the you get a cat failure. Do the O2 mod and it won't come back.