So im thinking about installing a y pipe on my 99 I30. But upon my inspection...she has big *** pre cats the one in front right under the exhaust manifold...and the other in the middle of the motor. And there's no o2 sensor behind the cat. So...warpspeed seems to be the only y pipe to make them for CA 4th gens. If I was to install the o2 sensors with that y pipe installed wont that make the check engine light come on? If so is there a solution for it?

 

If your ypipe doesn't have sensors after the cats you don't need Cali.

 

Ok. Here's the set up. In the front I have an o2 sensor before and after the "pre"cat. The in the rear bank I have an o2 sensor in there. And the other one is under the car where the oil pan area is. But as for the one behind the main cat...I don't see one.

 

Ok sounds like Cali. Every obdII car has one after the cat. Someone may have deleted it. The wire comes from a hole under the car below the drivers seat.

 

You indeed have a Cali Emissions setup.
You have one o2 on each bank before the pre-cats and one o2 on each bank after each pre-cat. There is no o2 after the main cat. Total (4) o2 sensors in a Cali Spec.

The Cali Spec Y-Pipe will keep the front pre-cat in place and only remove the rear pre-cat. It then moves the location of the rear pre-cat o2 to after the front pre-cat so it still senses a cat. You wind up with both pre-cat o2's looking at only one (front) pre-cat.

Us Cali Spec's don't get the full benefit of a Y pipe unless you swap manifolds, both the intake for removal of the swish valves and exhaust so you can use Fed Y pipe and use o2 sims to simulate the now deleted (2) o2's for the ECU.

 

I know this may sound cheap...but can I grab the exhaust manifold and the lower intake manifold from the junkyard? O2 simulators? Has anyone had luck with those?

 

Anyone?

 

You can just use the Fed Spec exhaust manifolds, O2 simulator and a Fed Spec Y-Pipe and you should be fine.

 

i believe this to be a true statement. U dont need the intake manifold.

pulling the exhaust manifold will be a chore. Not worth it IMO

 

That's why I only wanna replace the front manifold. Because someone said the gains aren't impressive compared to a fed exhaust. Plus I read in a thread where the intake with the s? Valve actually have little gain over a regular intake. Ill be honest no bs. But my friends SE-l, my dads gxe, and my old se felt a little breathless on the top end compared to the i30, they even said it themselves it feels like it has more ***** on the higher rpms. When I had my ve that one had a y pipe and man what a difference, the exhaust had sound nice too. I was thinking about swapping the intake too.