MatSLO
I'm Awesome
You haven't said the total miles your truck has done or why you are replacing the spider. I just changed the inlet manifold gaskets (they were shot) but skipped changing the spider as I run mainly on LPG. I did have to run on gasoline last week and it ran sweetly.
What I'm saying here is unless you absolutely need to change the spider don't. Instead, leave it until you have to change the inlet manifold gaskets and do it then (if at all). And change the inlet manifold gaskets at the first sign of them failing.
The truck now has 192 kkm (cca 120 thousand miles).
Perhaps I don't need to change the spider yet but I probably have a bad fuel pressure regulator. The truck won't start when hot unless I fully depress the gas pedal on startup. And I figured if I pay the mechanic to dig this far into the engine, I might as well get new injectors too...
I also sometimes feel like the engine has slightly poorer performance than before (in gasoline or LPG mode, regardless).
The reason why I changed ignition components and the the inlet manifold gasket in early 2017 is because my truck died in late December 2016. I don't know why I thought the gasket was to blame, or ignition, but I went ahead and purchased it all. After Christmas, my mechanic found out my fuel pump died... oh well, so much for my diagnostic skills.
Anyway, the fuel pump was replaced then, along with the ignition components (I bought the truck in late 2014 and had no idea when any of them was last changed). And the intake manifold gasket (already purchased it and the truck was in the shop anyway so I thought, why the hell not).
I definitely didn't regret changing the ignition components - while it seemed like my truck ran OK before (until it died), after that I noticed a huge improvement, much smoother running and better perfomance. And it wasn't just because of the new fuel pump, because it ran just as nice on LPG as on petrol.