split-reduction

My turbo conversion in '77Z uses a stock '82 ZXT ECCS system, with manual a boost controller running about 9 pounds of boost. The engine runs fine for most driving, although it seems to stumble a bit occasionally when starting out from a stop sign. The main problem is when accelerating hard it stops pulling at 4500 or 5000 RPM- it may rev a bit past 5000, but isn't really pulling anymore. I had thought maybe the valve springs were weak, and replaced them with a set of springs from a motorsport cam kit I had in another Z. That didn't make any difference. My mechanic told me the ignition system was poor. I've replaced the coil with a replacement Echlin coil, and new 8 mm high performance wires, but that didn't make any difference either. I also replaced the fuel pressure regulator a couple of years ago. One thought I had is that the fuel pump ,modulator is going bad. I've heard you can bypass that , but I didn't see any post that explained how to bypass it. Does anyone have any ideas? There doesn't seem to be anyone in my area who knows much about these or how to test them. Thanks.

Thanks for the reply. I did forget to mention, I am still using the Nissan ECCS computer and Nissan ZXT wiring harness, and I'm surprised that any coil would work since everywhere I've checked out for aftermarket coils specifies turbo only. I've got a stock coil or two from non-turbo Zs- guess I could try them and see what happens.

My mechanic says that my plug wires need replacing and the coil on my 280ZXT (in '77 280Z) is only putting out 9KV and should be 15KV. He is suggesting this explains why my car is not preforming well on hard acceleration. I plan to get upgraded plugwires, and have looked for aftermarket coil replacements, but the only high-performance coils I've seen are specified for non-turbo cars. Does anyone know of a high-po coil that could replace the one on my turbo or am I stuck with replacing with a new stock coil? Thanks.