need help

OK. I have a 1998 P71 since december of 2000. The car was originaly from Ct state police #12 which was a K9 unitand purchased with 76k. I did some modifications( i got a"new" used exaust of a 2001 P71with 12k, brakes, new 3.55 gears. all parts under the car are MOOG parts , ADCO swaybar, 2001 PI shocks. steering box,2001PI intake manifold, 2000 town car seats, steeda pulies ,Marauder exaust tips. The car now has 109.867 miles on. I want to get the Reinhart package (Marauder MAF airbox,chip. t stat. plugs), ADTR air intake tube and bigger trottle body. Can someone tell me em i going to gain any power in the car,also i want to ask what else can i do to gain power and better performance?I am new at all of this , how long can i expect this car to last? I have all the maintaince records and i been keeping the car in good shape .Thabnk you for your help.
ps :i am sorry for spelling mistakes ,i am typing with my left arm ,right one is broken

You will gain some power, mostly hp not as much torque, but your gains will increase dramatically if you open up te exhaust as well either with some headers and/or a cat-back. Remember though, if you can't do both cat-back first then headers and if you're looking for torque go long tube headers but if its top end hp go shorties. An upgraded ignition system will also give you a little power but a ton of tune ability. Another thing that would really help would be a computer reprogrammer/flasher and if in the budget a custom dyno tune, make sure they tune fuel as well as spark timing (most places just do fuel).