Originally Posted by
stndrd
You are better off using the s4c ratios and fitting an aftermarket LSD & final drive, along with a bearing & synchro kit. This gives you piece of mind that your box is 100% instead of purchasing a second hand box that you don't know the condition of.
But before you go and do any of that, when was the last time you did a major service on it (replaced all fluids & filters, spark plugs & leads)? I would start with that before spending any money on modifications. While you are at it, carry out a compression and leak down test so you know the health of the motor and go from there.
Also, on a B16A2, there is no need to change intake manifold to a larger volume one, as it will cause you to loose hp everywhere. The only reason I would change the manifold would be if you were to do a LS/VTEC or B16/B18 engine combo.
The LS/VTEC build is where you take a B18B or B20B bottom end (which are massive torque producers due to the stroke length) and fit a vtec head to it, increasing the performance of the engine greatly for not alot of investment.