Limited
I've 'played' with my '84 engine for years and made small improvements. Despite chip changes, my car always ran very rich after changing the camshaft.
I noticed little change when I went to the enlarged TBs, probably due to the restricted intake, which cannot be enlarged. The manifold just does not have material that can be removed to allow more air into the engine, hence the low peak power RPM. I hear that there is an aftermarket manifold that is much better.
A pal ran his X-fire with nitrous, twin 150's on a 406. It scared him nicely; then he added safety switches which kept the bottle off until above 2000 RPM. He has since switched to TPI at great expense.
The change in cam has to be carefully done as the stock intake severely restricts max RPM. You might kill the excellent bottom end with no resulting top end improvement.
I changed from 3.07 to 3.73 rear gears which made the car faster off the line, but was not satisfying to drive as 'the show' was over so quickly with the 4600 RPM drop-off.
I'd start with good headers, (coated with a great ceramic), mufflers and ensure that your cat is not restrictive.
I have a used set of TRACO headers, which I believe will clean up and coat nicely, plus FlowMasters which I can send to you. I'd part with them cheap, as I now run a 406 with TPI and a 3" system. That is a project I cannot recommend for most people. Hell, few shops would do it!
The above would give you a nice start. I also am not using the old intake and TBs, which would look much better in some else's garage!
