1) mostly because of hoses old and brittle...just replace..no smell 2) no 3) 90 auto's ..but its a crap shoot..some are good 4) 9psi is stock..doesnt vary in different gears 5) dp's = faster spool ...ECU 500-600$ and about 75-90hp gain (get an intake, and exhaust first) 6) 10-12k ..thats high miles, do a compression, and leak down test.