Dude, I already know I can’t get that much torque from a naturally-aspirated I4. I’ve stated further up top that my plans included a two-stage turbocharger.
And 3.0L is pretty damned big for an I4. I’m sure Porsche had to engineer balance shafts into the design to counteract the second order vibration. There are several other I4’s that had to use balance shafts like the one used in the Ford Tanus.
If you go to a lower numeric ratio to drop the RPMs, you will reduce power to the road. Usually people who want to be quicker increase the ratio.
If you’re running twin turbos on a small displacement engine, you’ve already resigned yourself to uneconomical operation. Those 400+ HP Civics running upwards of 25 pounds of boost get about the same fuel economy of a much larger V8. That’s the nature of the beast, the more air you shove into an engine the more fuel to have to shove in there as well. As for engine lifespan, even if you use forged internals, the more boot you run, the greater stress there is on the engine. A stock Civic may be good for 200k miles without major repair. Running a lot of boost you will be lucky to make it 20k miles without some major failure.
If you wanna go all out with some raw power, nab a Chevy 350 v8, then get a stroker kit for it, maybe even a super charger too.
As you can see in the video, the hood looks like a stock hood, so a v8 will fit under the hood. Just lots and lots and lots of reinforcing and upgrading components.
If you want to go for the ricer look, atleast the large spoiler will actually count for something, and the fart pipe mufflers might help muffle that nice rumble you’ll be producing
A Chevy engine? This may be a bit too close to a Corvette for the OP’s taste.
I’m not at all into rodding Hondas so any parts availability as to gear ratio changes in the transmission are unknown to me.
My feeling is that this won’t work for 2 reasons.
One is that you’re asking a lot if you want to drop the RPMs from 4000 down to about 2500 on the road and it would be a real stretch for a gearset to move that much.
Two is that even if you could get a higher ratio like that you’re going to own a dog when those gears are being moved by a peaky 4 banger; built up or not.
I did a gear change on a Chevy a few years ago in which the axle ratio was changed from 3:42 to a 2:56 (less than .9) and it dropped the RPM by about 800 or so; and this was on a small block V-8 Chevy.
Keep in mind that lower RPM does not always translate into increased fuel economy.
There’s a certain point where the “lugging factor” comes into play.
ok ok. Maybe he can get a 390 Ford racing engine. 
I just mentioned the chevy 350 since those engines are fairly easy to find parts for and cheap to buy preassembled