Originally Posted by JonBoy

Yes, right now he's using bolt-on equipment. However, I think if you add it up, he's pretty close to $25K-$30K just in parts.

Wheels - $3K
Tires - $1.2K
Exhaust - $1.5K
Seats - $2K
ECU + tuning - $2K
Body kit + install - $3K
Paint - $1.5K
Bracing - $1K
Oil cooling kits (engine and diff) - $1.5K
LSD - $1K
New catalytic converter - $0.5K
Endless Brakes - $5K
Custom Valved Coilovers - $3K
Steering wheel - $0.4K

TOTAL: $26.6K

And that's not even touching any bolt-on engine mods he might want, forced induction, roll cage, any chassis work (seam welding, weight reduction, lightening, etc, etc). That cost also doesn't necessarily include labor costs to install the different parts, which is probably another couple thousand dollars at typical shop rates.

Future work:

Forced induction - $15K
Tuning - $2K (he'll want it perfect)
Reinforcements to body and frame (engine bay and sub-frame bracing) - $1.5K
New clutch/flywheel/pressure plate - $1K
Roll Cage - $3K
R-compound tires - $1.5K

TOTAL: $24K, not necessarily counting install costs either

So, he has a $40K car (Touring + Sport with Navigation), $26K in mods right now and at least $24K to come, which puts him at at $90K and doesn't necessarily include installation/labor costs or development time if they have to go with custom work on the car to get to where they need to be. That's not the price of a GT3 but it's more than you'd pay for a Nissan GT-R which will still be quicker and have a warranty.

I know these cars aren't supposed to make sense (heck, the J's S2000 is well over $100K in parts and labor, including the initial purchase price of the car) but my point is that most people won't spend this kind of money to modify when they can just buy something else off the showroom floor with similar (possibly better) performance but with a warranty and probably more comfort.

This is a neat engineering exercise but it's a foregone conclusion that you can make just about any reasonably focused car faster than a more expensive, even more focused car by throwing money at it. It's just a question of whether it's remotely worth the time and effort.