I get the concern of the OEM parts with higher mileage. As a matter of fact I had a tune installed on my truck quite a while back. Initially it was bad ass. As I drove it more I slowly noticed the performance dwindling. Finally, there was almost nothing as I hit the accelerator; just check engine lights, and limp modes.
I narrowed that issue down to saturated sensors; with water, oil, etc. I drilled the stock intercooler, and nothing but nasty oily crap came out. It was at that point I purchased the following:
1. Full Race Oil Catch Can 2. Full Race Intercooler 3. Full Race Throttle Body Spacer 4. TurboSmart Mechanical BOV 5. Full Race CAI 6. Custom Tune
The tuner was Elite Performance and Tuning in Littleton, CO. Eddie, the master tuner, recommended that he throttle-back his tuning a little due to the mileage on my vehicle. Though I wanted the absolute most outta my install efforts of the items listed above I didn’t want my truck to blowup in the process. So, without replacing all those listed in your Livernois estimate I just decided to scale it back a bit.
Not sure how much power your looking for, but I’m pushing good power to the rear wheels in my Expedition; over 400hp and over 600lbs pr/ft of torque. Good luck on your build.
I have had all good experience with Livernois and the people working there. Like mentioned above there are going to be some tools and what not that are not your average tools you buy at Home Depot, there is a lot of knowledge and experience that goes into building the motor. It comes down also to how much you trust that you can do it right as you learn to do it as opposed to someone that has done it 100 times and knows what to look for and what not to do. Just my 2 cents