low_life77
+1y
(This is all depending on if you have the 2.0 or 2.2 I have the 2.2)
I would think first off if the motor was carb'd the first thing I would do is convert to EFI. I have read a lot of threads on mazdatrucking from several guys that have done this conversion stating that they noticed quite a difference in throttle response and a more top end power up to 5,500-5,600rpms. Even over the 32/36 Weber carb. Plus it opens up for more options like.................BOOST! Check out this thread...
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And if you do that conversion (or if yours is already an EFI motor) then the basic bolt-on's will help. Intake, header, high-flow cat (or no cat). And there is always the 12V head conversion. I have read guys doing this swap too and noticing a difference in top end power i wouldn't think much tho being they're pretty much exactly the same except for an extra valve per cylinder which I suppose would breath better but not for sure if it would be worth the hassle with the clearance issue between the firewall and dizzy.
You could also do what you suggested, upgrade your top end. I haven't done a lot of research on this so I'm not exactly sure what is available. But I have seen and read about ditching the factory 2.2 cam for a 272 cam which then I believe (though I'm not sure) that you would need to upgrade you springs as well. But that too should help gain a few more rpm's out of her and more top end power.
Then there is the obvious choice but a bit more pricey and time consuming, but you could always turbo it. Depending on if you are running a carb or efi set up will determine your limitations. I have been told by AngusWilly (turbo expert in my opinion) that on a 32/36 Weber carb you can run boost up to about 5psi before your fuel system will cut out and cause your turbo to bog. If you are running efi you will be able to run 8 psi safely but will also require you to upgrade your fuel pump with options like a B2600i drop in pump or a electronic pump. You can build your own boost set up or run a Probe/MX-6 factory manifold,turbo,harness, and ecu and run factory boost up to about 8psi all day and will notice a big difference! Even with the carb set up and 5 psi you will notice quite a difference.
Anyways I hope this helps although I know there are guys that know WAY more about this than I do I just figured I would throw my .02 in and anyone that reads this feel free to correct me please because I am still learning and would love to know!
Chance