I now have a CEL on in my Si after my high flow cat broke apart inside and kicked out the O2 sensor. I'm curious which would be the best way to go if I should just buy a new cat. and replace the O2 sensor or buy a P28 ecu and convert over to OBD1?

Tell me what you guys would recommend.

 

it depends on what your plans are with the car.

if you wanna build it whether it buy FI or NA, then i'd just convert it now, using the p28 and have it chipped and burned with a basemap for a stockish b16 (if that's what you have)

if you just plan on having say I/H/E and rockin it like that i'd keep it obd2 and get a new cat and o2 sensor.

 

obd1 is always going to be a better option since it's much less restrictive. But can't you just buy a new o2 sensor for cheap?

 

no it will not always be a better option, even if your ECU is less "strict" when it comes to what will trigger a CEL, does not mean the area you live in is less strict in what passes smog on your car.

No the OP cannot just buy a new o2, the cat broke apart. if he were to replace his o2 then he would just have another CEL, this time a p0420 for catalyst efficiency below threshold bank 1

 

we dont have smog and OP forcedfedferio is correct... if you're going to build the car whether FI or NA then do the obd1 conversion with the p28 and like he said "stockish" basemap... (phearable.net is great on service and cost) and again if you're not going to build the car and do just random bolt ons, replace the cat and o2.

 

Well it's just an I/H/E car right now. It'd like to just do some cams and things to make it a little quicker right now. But s turbo might be an option in the future.