Hi all I'm looking to lower my vtec to 4000 rpm and also install 4.56 or 4.77 rear end but not sure which I should go for on a stock F20C AP1? Anyone have any experience and could chime in? Hardly do any highway driving..

 

I would 100% opt for the 4.77 if everything else is AP1

 

Two different projects. The differential change is just wrench turning. You can have it done in an afternoon and may not "need" to lower your VTEC right away.

Of vice versa!

Lowering my VTEC required a high flow cat and fairly expensive tuning which can't be done on your ECU so you'll need an aftermarket. But the power just rolls on at 3600rpm in my case and I've not given a thought to messing with the differential.

Or ...

Supercharge the car and skip all this.

-- Chuck

 

On my previous setup i had an f20c with with 4.56 gearing. It felt nice more aggressive on street/city driving, but also increased noise levels and amount of shifting. Dropping vtec will definitely enhance the feeling and driving experience. And you will also have to correct your speedo or get used to it being off. I used the yellobox speedo solution to correct it.

I did a lot of highway driving so my RPM were always around 5 - 6k going 75 - 85mph in 6th with the gears and 17" wheels.

 

This is great advice and I totally agree, but I'm wanting to do a couple mods and pretty much keep the rest stock. I do have a K&N CAI, but the rest of the car is bone stock including the exhaust. Maybe I will need to modify the exhaust. What ECU and tuning software did you go with? Do you recommend KPro or a different ECU entirely such as a standalone/piggyback?? Thanks!

 

I would love a more noisy rear diff. I love the sound of gearing in fact that's a plus for me! As for more shifting, of course that will come with the trade of a higher rear end ratio and you can always skip gears driving through the city.

 

Choice of ECUs is best determined by who will tune the car. I'm Gernby FlashPro tuned as no aftermarket ECU required on the 2006+ cars.

-- Chuck

 

Consider doing the diff change first and seeing how much it wakes the car up. I went with a 4.625 FD ratio for my AP1 last year, along with a greddy emanage with karcepts tune, which lowered vtec to 4k.

After having some driveability issues with the tune (random stalling), I unplugged it and I don't really miss it. The gearing change was the bigger improvement by far in terms of waking the car up.

Check out my vid about the mods here:
And more recent vid with the tune unplugged:

 

Having had the 4.77 gearing for years, it was nice but highway driving RPM's were way too high to be comfortable. 4.56 if you must swap out gearing in the diff. AP2 Tranny is really nice though I must say, shorter 1-2 and I think 5-6 are taller slightly.
My car is a bit of a Frankenstein('00 body, '02 Engine, '04 Diff, '00 driveshaft, '06 Diff, '00 half shafts, AP2V2 wheels). Running on a Hondata K-Pro and a high flow cat(stock '00 headers & '05 exhaust). Love the look of the oval tips!

 

4.44 as i have seen has been widely recommended; I'm a car noob so im just curious how something like the 4.56 or 4.77 would differ from the 4.44.