I understand where you come from...
Believe it or not, up until four months ago I used to drive my truck on the street as my DD. (the truck has lexan window on, no airbags, no A/C, no radio, no P/S, no windshield wipers, one bucket seat with 4 point harnesses already, a fuel cell tank, and a standalone to go with it)....not exactly your typical street-legal vehicle I may say....
It's funny you mentioned "mind-boggling even for a typical ''tuner car."
I have a little story to tell:
The other day I picked up the latest issue of "Import Tuner", not exactly my cup of tea (actually I think it's garbage)....anyway, I picked it up because there was an article about Jun Auto (a Japanese tuning company)....and the current chump of "Import Tuner'' interviewed the Honcho of Jun (Susumo Koyama)....in the interview Koyama san was generalizing and stereotyping about the average american ''tuner''......saying that too many Americans focus primarly on HP, and loose sight of everything else....not carrying about longevity of the engine, and other important area's of the car.
He kept saying: "for them (Americans) it's more important the price of the item (installed on the car) rather than its quality, and where it was manufactured."
Furthermore he said that because of that, American tuning is far behind. (comparing to the Japanese).
I have to say (with all the respect)....that I agree with Susumo Koyama in what he said, I agree with him....after being here in the States for over 13 years..(and lived in Japan for about 5).....everytime I get into a discussion with someone about cars, HP is definitely up on their list....
That's their philosophy....and I respect that....
But that's not my philosophy....
A car needs balance in EVERY aspect.
How many times I read an article stating: "the car is putting down an healthy 600 hp,....blah blah blah......in order to hook it up, the owner swapped the stock spring with Tein S, or K sport coilovers, or Megan Racing coilovers....."......such and such.....to me that's ridicolous.....it's sad actually; that the owner of the 600 hp car focused primarly and solely on engine upgrade, and maybe he/ she ran out of $$$, and cut corners with cheap knock-off sh!t from China. Rather than do the other way around.
A 600 hp car (for instance)....HAS to have the best suspension possible (Moton, Ohlins, Penske, Sachs and so forth) to handle it's power....Megan Racing won't cut it......I don't understand the mentiality and the point of view of those folks.
With that said. I know my truck (the Tacoma)....it's VERY far from being a race-competitive machine....however, I am doing as much as I can to ''close'' that gap.
My engine will NOT produce humongous HP (only 300-320)....which is nothing to today's standard....but I will make sure the suspension will have the very best components I can afford, (as well as wheels/tires).....along with a solid roll-cage (not over-built) and a functional cockpit, forget about those Defi gauges, and bling-bling sh!t.....function over form.
When I will be done; sure it won't look as sick as an Impreza Sti or an EVO 9.....but I will be happy to say that I build my truck my own way, without opening a catalog and order a bunch of parts (anybody can do that with $$$).
How many people nowadays you hear saying: "oh I built my car".....:disappoin
How hard is it to bold on stuff ? All the car mentioned above have a HUGE aftermarket support. It's too easy to open a catalog and chose what you want and pay; and went it comes in, just bolt it on. And they claim: "yeah....

....I built my car".........wow....:disappoin...impressive.
It's not very far from being a LEGO, is it ?
Alex
oopps, I forgot to answer your question.
As far as ''specific modification-level category"....obviously the truck will only be allowed to run in the unlimited class.....yet still be somewhat stock from the un-trained eye....