is there a amp in the 99 ssei if sp where is it and how many wattage and what not ?

does your factory radio says bose on it? if not than it doesnt have a factory amp. I am not sure exactly on the wattage but id be willing to bet its around 35 watts to each channel. I have been thinking about it alot and I really need to get my hands a bonnie with a factory amp so I can figure out the wiring codes and all. I hate factory amplified systems.

it is a bose system...now is it gunna cause problumes when i go and installe the aftermarket amp subs and speakers... the head unit i have supplies 54 watts X 4 channels so it would be louder if i bipassed the factory amp for my speakers?

You have to be careful with the head unit you pick out. I have listened to some "60 watt"
per channel radios that sound horrendous, and you replace it with a 15 watt per channel decent radio and it sounds much better.

The easiest way to put a sub and amp in would be to use a line level converter off the 6x9'* in the back, they are generally only getting bass anyways. Then you can keep your factory radio in as well.

The right way would be to scrap the entire stock audio system, but that is quite the financial burden, and takes a good amount of time.

im useing a sony xplod head unit ...it has been put in my 96 merc sable station wagon that wasent to bad with 15 inch subs and 200 watt amp...now im looking at 2 15 inch pro comp clearion subs 1500 watts a peice and 700 max rms...my amp is 2000 watts max and 600 rms X2