Not sure how crazy your going or what your power goals are, but I'll assume you'll get the 275 whp kit and do full installation of everything yourself, just to make this easy. Hopefully, you have the revised pistons in your motor (late 99 to 2000). I ran the .63 on my 3.0L with the ADC kit and could have made 400 whp, but its really up to you. With a 2.5L, you could probably get 350 whp out of a .63 but not with the base NPG kit. The .82 will definitely make 400 whp on the top of the line NPG turbo kit.
This is what I would consider bare essentials:
NPG Turbo Kit + Turbonetics upgrade - $3150
X-CAL 2 - $380
Battery Relocation and wiring - $100
MSDS Headers and y-pipe - $700
Aftermarket Catback or Custom Exhaust - $600
SPEC Stage 3+ clutch - $450
SPEC flywheel - $350
Quaife LSD - $800
Driveshaftshop Stage 2 Axles - $700
DMD - $80
Larger brakes - $400+
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$7710
If paying someone to install your turbo kit, clutch, lsd, etc expect about another $1500 ($9,200 total) just to be safe.
If your shooting for 400 whp, then you'll need the upgraded ADC turbo kit
NPG Turbo Kit + Turbonetics upgrade - $3525
X-CAL 2 - $380
Battery Relocation and wiring - $100
Lightning 80 mm MAF -$100
MSDS Headers and y-pipe - $700
Aftermarket Catback or Custom Exhaust - $600
SPEC Stage 3+ clutch - $450
SPEC flywheel - $350
Quaife LSD - $800
Driveshaftshop Stage 2 Axles - $700
DMD - $80
Baer brakes or equivalent - $850
Guages and gauge pod - $300
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$8935
Again, if your paying someone else to do it, expect at least $1500 ($10,435 total)
If your going for your all out turbo build not skipping anything.....
NPG Turbo Kit + Turbonetics upgrade - $3525
Pauter Rods/Diamond Pistons - $2000
Battery Relocation and wiring - $100
65mm throttle body - $50
Max Extrude Honed UIM - $300
X-CAL 2 - $380
PNP Heads/ST220 Valve Springs from Kinger -$1500
Lightning 80 mm MAF -$100
MSDS Headers and y-pipe - $700
Aftermarket Catback or Custom Exhaust - $600
SPEC Stage 3+ clutch - $450
SPEC flywheel - $350
Quaife LSD/Post 2000 shift forks/zetec final drive - $1500
Walbro 255 lph fuel pump - $100
Driveshaftshop Stage 3 Axles - $1000+
Pole120 Roll Resistors - $200
DMD - $80
Baer brakes or equivalent - $850
Guages and gauge pod - $300
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$14085 (or $15585 with labor)
I'm sure this is low for every one of them. Obviously, there are things you'll run into that you'll need like gaskets and such. I'm assuming you won't be installing clutch, flywheel, LSD yourself. If you are, you will need an engine puller which is more money. If you had all the parts ready to go and were able to complete this without any snags, you could probably do the 1st option in a weekend with some help. Realistically, it will be down for a 2 weeks minimum. Nothing ever goes as planned as I've found out. Bolts breaks or are rusted on, gotta buy replacement parts Saturday night and you have to wait until they open again on Monday, etc.
NPG mail order tune will be more than sufficient.