90' CRX HF-T hypermiler?
 

Well, I have a 1990 Honda CRX HF. She's got almost 230,000 miles on her, and she runs like a dream. Minimal to non-existent oil burn (doesn't even show up in a 3k oil change), no coolant burn either. I've kept her very well maintained.

However, my catalytic downpipe has rusted out.

I've got three options.
1.) OEM used replacement, also see "boring"
2.) Ebay 4-2-1 stainless see "kinda boring"
3.) HF mani + T25 + DSM sidemount = yesplz!

So what say you, HMT?

HF manifold with an adapter, run a T25? I'd be changing the wastegate spring out, downswap to 5 psi, or my other option of adjusting the wastegate to where the boost onset is delayed slightly.

I'd like to run a DSM sidemount as the intercooler. No sense using a huge front mount for this build. I would also like to ideally keep my stock 240cc injectors.

I'm not really looking for a huge power increase, moreso gas mileage. I read a story about a guy who turbocharged his S2000. His MPG went up approximately +10 mpg! The less time you spend accelerating, the better. Also, a turbocharger obviously helps make better use of wasted energy anyways.

My questions though:
1990 HF did come with 240cc injectors, correct?
What tuning program is popular these days for OBD-0 cars?
Can I keep AC?

I don't mind switching to an EG Civic radiator. A 1.5L does not not a radiator that takes up the whole front of the car.

OH! And I don't mind running water injection as well.

I used to get 38mpg in my n/a g1teg.

Put on a 14b/hf mani and now I only manage around 34mpg. You will not gain fuel economy by adding a turbo, you will begin flooring your car pulling away from every stop sign.

Your best bet for increasing your fuel mileage is going to be aero mods. Making a lightweight "skid plate", etc should be good for a few mpg.