If you buy it, switch that air intake back to a stock one.
You can just replace the filter.
Looks nice, but you should swap that intake for the stock one. It fits better and doesn’t take in hot air from the engine.
I had a 00 type SH, and I’d recommend going for the base model. ATTS is old technology, and while it was great when this car was new, it had issues. It could overheat and shut off. If too much power was sent to the wheels or if it was lowered too much, it would shut off. The base model is better because it doesn’t have all those headaches. Plus, a good limited-slip differential will do just as good a job as the ATTS. The aftermarket options aren’t great for this car, especially the SH. It’s a decent car if you want to keep it stock. Just check for oil leaks; mine had a lot.
If there’s no record of the timing belt, water pump, and tensioners, get those done right away. Also, check the suspension; the shocks and struts are probably worn and rusty. Those are the major points, but there are other things to check too.
It really depends on the current condition and what parts have been replaced so far.