Thats cause the kits all cost more than a V8 swap and didn't get as good of mileage far as I saw on the couple I got close to.
A lq9 chevy small block with variable displacement including trans and tcase can be had for around 3500 than add about 800 for motor mounts and another grand for a computer.. almost 400 HP and about 500 ft lbs. and should get 22 on the highway..
Both the blower kits I saw were north of 5K and only got you about 250 HP..
<shrug> who knows what reality really is with the blower setups..