"Some of those prices seem a bit high. "
Yes, they are. Some of the cost is with the high cost of parts like the german TTP brand, which are built to a high standard, but are very expensive. Headers about 1500.00, cats cost even more. The TTP carbon fiber cold air intake is 850.00 and that is not installed. Also, I bundled several things together with the costs and did not list everything, like a B&M short shift kit, that sort of thing.
When I bought the car I had about 7K that I had put aside for mods, that is what started me down the slippery slope. All I do now is enjoy the ride, and a fine ride it is, always brings a smile....
Ed