well if you have the choice, then definetly get the p5, i wouldn't trade it for anything, i got a 2002.5 midnight blue and it never ever ever gave me any problems at all. As far as the room, i have a 3yr old boy(booster) and a 8 month old boy(regular front facing car seat) and they have no problems at all. Plus we drove all the way from florida to kansas which is about a 1k trip and didnt have any problem, mind you that i have the obvious exhaust, cai, and headers but not to much noise on the road, just throw some tunes on and you'll be ok. Although they tend to rev a lil high above 80mph but you shouldnt be worried about that with 2 kids in the car. Oh yea..and im dropped about 2 1/4 inches on low pros, i bought my car brand spanking new in late 2002 with 5 miles on it and never had to take it to the stealership once for problems. Plus in 2005, being that im in the military and overseas, my wife went back to florida for the time being, and drove my other car that was left beind. Well from jan-2005 til nov-2005 the car just sat quietly in some friends of the family driveway, with a car cover ofcourse ( poor thing, she probably thought we abandoned her ) and when my wife ( not the most mechanically inclined person ) went to start her up she turned right on with no problems as if she had been driven the whole time, which she hasnt becuase she took all the keys ( dont really trust ppl, lol ) and although it was a gamble to let the car sit for that long, i had confidence in her and she proved me right( damn i love this car). Of course the first thing that i told her to do was the normal tune up at the local shop. so anyway after all this, in conclusion, yes definetly get a p5. And if you don't im going to be pissed because i just wrote all this for nothing!!!!!!! (poke)
p.s. I have driver, passenger, and side airbags in my car. Not sure if there is a diff with side curtain airbags or not, but i do have side airbags.