those catalysers they sell on ebay, wich seem to be only a straight thru tube... i wonder if some sort of ecu error will show up if i put one of them my gsr obd2 98

 

i had one on my 97 gsr obd2.. it threw a CEL and i lost power because the secondary o2 sensor was reading diff. numbers than its supposed to.. thats why i got a chipped p28 ecu with a obd2-obd1 jumper harness because it doesnt read the secondary o2 sensor.. no more problem with the straight pipe..

 

more than likely those "cats" are really just resonators and yes you will throw a CEL :down: