# '01 Maxima upgrades



## fett (Mar 22, 2005)

I'm looking for increased low end / mid range power(20 hp). Local shop wants me to start with a CAI / catback combo. and a tune up. He has concerns that Y-pipe would really lower back pressure and affect off the line performance. Could this happen ? Can the CAI be a problem in frigid winter weather ? Thanks.


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## Puppetmaster (Mar 28, 2005)

fett said:


> I'm looking for increased low end / mid range power(20 hp). Local shop wants me to start with a CAI / catback combo. and a tune up. He has concerns that Y-pipe would really lower back pressure and affect off the line performance. Could this happen ? Can the CAI be a problem in frigid winter weather ? Thanks.


A y-pipe is still the best mod for power throughout the powerband (about 12 whp on your 3.0).... an intake has minimal gains for the money ya spend, and a cat-back is even worse. Eventually, ya do want to free up the flow in the rest of the exhaust, but an intake/cat-back combo will only really be effective if ya already have a y-pipe or aftermarket headers. 

If ya do wanna get an intake, look into the Place Racing/Cattman CAI, Berk WAI, Frankencar WAI, and you could even try the Ghetto Air Box, which has been dynoed by some guys with 3.5s to give 9 whp (both manual and auto). Link is here:

http://home.insightbb.com/~dwh/GAB.htm

Additionally, CAIs are fine in the winter, unless you're driving in water over 1' in depth, which, if ya are, you'll have more things to worry about that your intake.


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## Puppetmaster (Mar 28, 2005)

fett said:


> I'm looking for increased low end / mid range power(20 hp). Local shop wants me to start with a CAI / catback combo. and a tune up. He has concerns that Y-pipe would really lower back pressure and affect off the line performance. Could this happen ? Can the CAI be a problem in frigid winter weather ? Thanks.


Btw, about backpressure... 



> *BACKPRESSURE = TORQUE?*
> 
> An old hot-rodder's tall tale: Engines need some backpressure to work properly and make torque. That is not true. What engines need is low backpressure, but high exhaust stream velocity. A fast-moving but free-flowing gas column in the exhaust helps create a rarefaction or a negative pressure wave behind the exhaust valve as it opens. This vacuum helps scavenge the cylinder of exhaust gas faster and more thoroughly with less pumping losses. An exhaust pipe that is too big in diameter has low backpressure but lower velocity. The low velocity reduces the effectiveness of this scavenging effect, which has the greatest impact on low-end torque.


This was taken from a great article on building your own custom cat-backs, which can be found here: 

http://www.magnaflow.com/05news/magazine/05sportc.asp

Or here:

http://forums.maxima.org/showthread.php?s=&postid=960160#post960160


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