I've decided to keep it.....

i don't know if its such a good idea but since all of the good things i've been hearing about the sr20 is good. i've heard about launching with the AT and hoe to hold the brake and gas @ the same time the let off the brake and mash the gas through. Does anyone know what the torque converter max RPM is in the 2001 SE? thanks. i want my tranny to last awhile and dont want to put a lot of strain on it by neuta-dropping is a couple months ago. Can i do this from gear 1, or do i have to keep it in D?

neutro-dropping will kill your car, plus it results in slower 60ft times due to excessive wheel spin, hold brake and gas and rev to about 2k and then dump the brakes and mash the gas, i actually beat my friends corolla s with my 1.6 litre gxe and he had 10 more hp than i did, just because i launched harder

i tried that today actually right as i had time. i couldnt launch higher than 2k i think i may need i higher rev torque converter o something. it seems I'm faster just puttin the car in 1 and flooring it right as I want to go and catch the torque curve @ bout 3k. But i can floor gas all the way and it wont go past 2k, mash the brake and pull right away. I'm not sure whats faster yet tho.

all auto SRs are like that. once you get some more power, that 2k drop will be fine. (my 1999 SE-L could chirp the front tires doing that with just intake and 2.5" exhaust)
the revs will drop too far and that sucks but neutral dropping is probably the worst thing you could do to a car(besides like not putting oil in or something)

if you live in SOCAL or somewhere with a lot of decent shops someone might be able to make you a custom torque converter with a higher limit

i know that from some companies that a high-rev torque converter can be ordered. How much more will the air be able to flow thorugh the engine if I have a CAI, header, 2.5 exhaust?

speaking of chirping the tires when launchin from 2k, it does that already, but will the CAI and full exhaust help me out imporving the torque powerband?

somewhat yes.
make sure its a decent exhaust though, otherwise if its poorly made, you could lose some low end.

oh and my car had 205/55/r15s so thats why i couldnt chirp stock, and the 01 sentra has roller-rockers and that helped low end torque a little over the 95-99 models

oh and as far as your first question, there is no real way to answer that...because it varies by brand of parts and by how well your cylinder head flows to begin with. i cant put a # on it but you shouldnt lose any low end with just those mods.