J31 max with 2004 4 speed auto
 

I've been doing a lot of reading on this site and others, and have come to the conclusion (after wanting to turbocharged) that nitrous is a much more economical way to generate a decent amount of power.

I am just wondering about how the 4 speed 2004 transmission will hold up. I'm already on my second gearbox, and have an auxillary cooler running in series with the stock cooler.

Driving the car in a reasonable and responsible way is obviously a big issue with these gearbox's, not doing burnouts and etc. But with sufficient oil cooling and either the DR mod or a Transgo shift kit I am sure that it can handle the extra power.

Does anyone have any experience in relation to the above? Thoughts, advice, criticism would be appreciated thanks

I guess that depends on how you're going to drive with the nitrous. Track only, first choice, make the DR mod or Transgo kit. Nitrous on the street, do those mods and keep a spare transmission close by. There are a couple of things happening in a stock 4AT transmission that kills them when running more-than-stock horsepower. The stock transmission computer modulates the voltage going to the A and B solenoids so that shifts are felt as smoother, but really slips internal clutches and bands. This is why there are custom shifters made for the 4AT. The other thing is the ATF fluid - there are always friction modifiers in the non-racing varieties ( Read: lets the clutches and bands slip). Amsoil has a Super Shift ATF fluid made for racing that doesn't slip the clutches and bands on every shift. Lucas also has one which I have used.

Nitrous has another problem for transmissions - the torque created by spraying is immediate - not based on RPMs - so if you spray a 100-shot you will have an immediate 100 WHP to deal with - through the transmission - until it dies.

I have had a company ( IPT Import Performance Transmission) build a couple of 4ATs for racing and the transmission is fantastic, and tough as nails. It took me 2 racing seasons to wreck the first one and the second one was going fine when I had engine problems. It is a 4AT from a 2006 2.5 Altima with a 4.5 final drive and a welded spool, but works with stock axles, all sensors and transmission computer connectors, and is killer at the track or on the street. Uses the Amsoil as well.