As the name suggests, I want to make this last. Now to contradict it by saying "How should I tune this thing?"
I like the power and how it drives now, but I can squeeze more and get a much better experience without having to go through the headache of buying a whole new car.
Here's my list of performance mods I want so far:

• Fast road cam
• ECU
• intake/exhaust(Y vs X vs H anyone?)
• Tranny swap(why does everyone use the altima trans? does it have to be manual(I might want auto-manual)?
• coilovers(brand suggestions?)
• weight reduction

So where exactly on that list does it stop being "I can do this myself" and start being "I need training/someone trained to do this"? I don't want to have a half-assed car but I also don't have money bro I just had to put a bumper on myself lmao
How badly could I **** it up if I, say, change the camshaft myself, assuming all reasonable precautions are made? "making things play nice with the ECU" shouldn't be too bad if I get an aftermarket ECU and whatever, right?

Also, any other advice making this car feel a bit less like a boat would help greatly seriously, the handling is not good.

 

You will get less of a headache and more bang for your buck buying a better car.

 

If you want it to last, leave the car alone and enjoy it as-is. The most I'd do on your list with this car is coilovers and mayble intake/exhaust, keeping in mind that negligible gains will be had with an exhaust/intake.

 

The funniest thing with tranny change is that probably your maxima will have better acceleration with CVT and no mods, than with manual gearbox and increased power.