CX tranny. Believe me, it's fun. I only really need 1st, 2nd, and 5th gears. I'd be happy with just a 3-speed. I did this D15B7 swap because the stock motor was shot. It didn't turn out so bad considering how much lighter the CX is than a DX.

My other car runs low 13's, and I plan on breaking it a dozen times trying to make it run 11's, so I didn't need to go nuts upgrading my fuel efficient daily-driver.

Here's my mod list...

Worn-out 1992 CX, 105k miles $2000
Complete D15B7s w/Throttle body/manifolds/injectors - FREEBIE! ZIP! ZERO!
Engine gasket kit $90
Machining the block (.020 over+honing) - FREEBIE! ZIP! ZERO! NADA!
1 exhaust valve - $11
Deck the head, regrind the valves, 1-angle valve job - FREEBIE! ZIP! ZERO!
Polish the crank - FREEBIE! ZIP! ZERO! NADA!
Exide clutch/flywheel combo - $175
Rebuild oil pump - FREEBIE! ZIP! ZERO! NADA!
Water pump $35
Timing belt $28.50
OEM T-belt Tensioner $35
VX tach-$12
Stereo from my totalled 95 GS Eclipse - FREEBIE! ZIP! ZERO! NADA!
Generic 2" muffler-$25
Polished valve cover $11.50+ 16 hours of hand sanding
eBay CAI - $36
Cousin's auto shop with lifts & air tools - FREEBIE! ZIP! ZERO! NADA!

On less than a Monster Garage budget, I picked up over 40hp, and shaved over 2 seconds off of the car's 1/4 mile time; that was with the WRONG injectors, running lean, and detonating with no tachometer or clue where the redline was. With the right injectors, I can already tell it's faster, no more o2 code-1 CEL's, and it doesn't idle surge or hesitate anymore.

Not bad for a civic + a weekend + $450. How much is an AEM CAI new? What gains does that offer? PTPTPTPTPT! If you're resourceful, you can swap the whole engine for less than the cost of a cat-back.

My advice: Never buy bolt-ons for a CX. It costs less with bigger gains to swap them with a crappy motor than it does to mod the even-crappier motor they already have.