questions from a nub

[5thhorseman]

hello all,i bought a 2007 base yaris sedan with 111,000 miles on it for $4000.,it is in pretty good shape but was the filthiest car i have ever seen,it was so bad i took it to a detail shop and gladly paid for them to clean it.the car was owned by a nurse and she got a new suv and wanted to dump it,she originally had it posted for $7500. lol.but after it sat on cl for 3 months she was ready to let it go at a reasonable price,the car fax is clean but i have a airbag light on and do not know if this is common,but it will go out when i first crank it up and back up but once im in drive it comes on again,it has to be a sensor or something.i also have a couple of questions, 1) i want to put a cheap cold air intake on it 2) i want to put a exhaust on it cat back axle back i dont care i just want a little sound but do not want to go deaf at 80 mph 3) cheap wheels and where to get them,help me out guys,the car is a auto trans,i work offshore and drive it 300 miles to work then 300 miles home every 14 days,[it has already made 3 trips] plus i drive it around town at home,[ sorry about my typing im on my tablet ] i have been looking on ebay and have seen intakes for $50, and bolt on axle back exhausts for $99. has anybody used them ?,the exhausts say off road only,is this a concern. ps i will post some pics as soon as i can get them up.