extractors

The fitting of extractors will be better suited if mated to a free flowing exhaust system - 2.5" or even a 3". So by the sounds of it a complete new system for your Cruiser.

There are 2 types of extractors - tuned length and interference. The tuned length are mainly suited for close to max engine rpms to have any effect on the overall performance. While the interference type ones will work well in the 1200rpm to 4000rpm range - suitable for low end stuff.

Both will improve performance but for different reasons due to their design. Fuel economy is argueable but should improve if any. Genie used to make really good ones (interference type) but shop around for brands / costs / warranty.

Depends as to how long you keep the vehicle but you could consider a stainless steel muffler too.

I put a set on my 1hz with a 2.5 or 2.75 (can't remember) and it certainly held the hills a heap better but top end suffered. 120 was the fastest I could go