the stuff they did actually does cost that much but you could have done things different. I assume you got new stock turbos. You could have upgraded to 13g turbos for about $1050 and solved the smoking while getting better turbos.
that's good that they cleaned the oil feed lines. but new ones from mitsu are only about $40.
It is definately not necessary to replace the intercoolers. Unless they have physical damage to them. They can be cleaned out very easy with some carb cleaner. And I would have cried for you if you paid $1200 for stock intercoolers. You could upgrade to a very nice front mount intercooler system for $1600 or less and get dozens more horses.
new spark plugs are no biggie. they probably put in platinums for about $60. I usually just use the regular NGK's for about 2 bucks a peice. no power difference.
by the way, the stock boost gauge is not a real boost gauge. it has no vacuum line connection. It goes off signals from the ecu. If you put in a real boost gauge you will see.
Where are you located? If you need work done bring it to me or to polk performance. I know more about these cars than any repair shop in AR. (besides polk) Hopefully you won't need any major work for along time
But for performance upgrades and basic repairs/maintenance I can help you along and save you some money. Look at my sig. I've done all the work on my car and I drive it everyday.
If you wanna chat PM me or call me. 501-952-7397
Marshall