ive wondered for a while if i would gain any hp by having a pipe made to replace the first pre cat on my 99 cali spec max..my ypipe does not replace this part of my exhaust i notice while browsing the Stealin catologue today that there y pipe has an extra pipe to replace that piece also anyone know?

 

wouldnt it trip a sensor?


Eric

 

it would throw a CEL. that precat needs to be there. thats how the ECU reads and adjusts your fuel mixture(through the O2 sensor).

 

The gains would be very slim, if any.

 

Someone did this awhile back....desertmax or something....anyway he switched out his cali-spec y-pipe and exhaust manifold for a fed spec y-pipe and manifold. The gains were minimal.

However, he did get rid of the front pre-cat and probably shed a few pounds off his car by doing so. He had a nice side by side comparison of the two setups and the fed-spec one looked pretty good. He had to relocate an O2 sensor by drilling an extra hole in the y-pipe (I think?) to fool the ECU into thinking the precat was still there. Something like that...

Anyway, I wish I could find the site...it was a good write up.

 

yeah i would def make sure there was an opening on the pipe for the o2 sensor and like others i figured the gains would be minimal but i was curious anyway if anyone had done this

 

He did the swap and gained alittle more midrange torque without the precat.

http://forums.maxima.org/showthread....ifold+AND+swap
http://www.desertpearlmax.homestead....noResults.html

 

It does not throw a CEL, the pipe is made so that the sensor that looks at the first pre cat is moved and looks at the 2nd remaining cat. The ECU has no idea which cat it's looking at, all it sees is a working cat so it things all is OK. Both pre cat o2 sensors remain on the car to monitor the a/f ratio of the front and rear cylinder banks.

Gains for us Cali Spec cars are in the range of 8 - 10 HP, not 15 - 18 like you Fed spec guys. It's still a very good bang for the buck mod.

Quick Note: I just put the Injen intake on my Cali Spec and the DynoButt feels better pull in the mid range area. Nothing lost down low, and a really nice roar at WOT! Combine an intak with a Y pipe and our Cali Spec Max's run pretty damn quick too!

 

I thought budget released their new cali spec y pipes with the extra piping any owners have this yet?

 

Last time I called, May some time, it was still in development.

 

so a y-pipe is worht it then? I wasn't really into getting one casue of the cat that coulden't be removed.
wish headers would come out with holes for the sensors. What about swapping the ECU also?

 

Even with just one cat removed the ypipe gives a nice power increase and its also like 13lbs lighter than the stock pipe if i can get the extra pipe to remove that first cat i will im sure there is some power there even if its just a few .. maybe i can just order that pipe from cattman or someone oh and im sure that fat cat weighs something to