I was thinking would the homongous piping on the NLEV Manifold hurt performance with a custom downpipe?(the precat removed)

Im thinking about doing it this upcoming week but Im worried about lost backpressure since the NLEV Manifold since to be alot bigger

Desert Pearl- How big was the opening of the manifold? 3"??

 

Two people, Desert Pearl and sleepermax, have replaced the front cali spec manifold with a fed spec manifold that does not have the pre-cat. They also put in a fed spec Stillen y-pipe. The results showed that gains were minimal. That shows that the front pre-cat in the cali- spec manifold is not very restrictive. So, unless you feel like doing the conversion, it won't gain you a lot of power...

 

im not talking about a conversion...im talking about removing that big ole precat from the manifold itself and bolting up a downpipe TO the NLEV manifold

 

Which manifold? The front manifold has a pre-cat built in to it if you have a Cali spec maxima. The rear pre-cat is built into the stock down pipe itself. When you get an aftermarket cali spec y-pipe the rear pre-cat is removed and the front pre-cat stays since it is built in.

 

isnt the front precat BOLTED to the manifold???...i always thought it could be removed...just a tedious job

 

Even if you could accomplish what you're suggesting, the net result would be either no increase in performance or a loss in performance. In addition, you'll probably generate a MIL light if you don't move your O2 sensors behind the main cat.

 

Pmpin' - it's a lot of work and performance gains are minimal, but driveability is noticeably improved compared to just having the y-pipe/single precat. You have to replace the front manifold - there's no way around this without getting negative results. It's a LOT or work - I would not recommend messing with the front manifold/precat unless you really miss and want to restore driveability to stock form, and you really, really like working under your car!