The D16y7 and y8's share the same bottom end right? The only difference between them being the Vtec head on the y8? (I mean, aside from the ecu, gear ratios and other obvious things related to the y7 being non-vtec and all...)
So would the upgrades civic1999 is doing to his y8 have similar benefits for a y7?
The first thing you should do is swap in the EX tranny! Your stock ECU and internals will let you run over 7K rpms (I do it daily on my DX!
). You'll get the most performance gain just from that, since torque on the Y7 is higher at lower RPM than the Y8 even though peak torque is slightly higher with the Y8.
But the VTEC conversion will boost the top end. The internals aren't exactly the same, the pistons are different but if you are swapping in the A6 pistons it doesn't matter anyways. But if you keep your Y7 pistons and put a Y8 head on you will actually have slightly more compression than a stock Y8, based on some figuring I've done...
The converter/exhaust is different from LX/EX, but it's no big deal just get stuff for the EX and then get an EX or aftermarket cat and your good. The O2 sensors I think are the same but the 2nd one is in a different location. You can solve this with an EX harness or by extending the O2 sensor leads.
By the way, if anyone wants A6 pistons, I have a source so tell me the best price you can get and I'll see if I can do better...