Those folk who tell you that you cannot combine aftermarket coil springs with standard shock are either:
- lying
- ignorant
- stupid
- greedy
- any combination of the above
By the way, the open and closed shock lengths of the standard shocks is the same as OME/IronMan/etc (Get the specs and see for yourself). In other words they all have the same stroke and therefore CANNOT increase your articulation.
In fact, in the real world stiffer coil springs can actually reduce your effective wheel travel because the stiffer spring rate will compress less for any given situation thereby reducing the upward (compression) movement of the wheel.
If I was spending my money on suspension again I would do the coil springs (your choice to go with a local spring manufacturer or an import) and combine them with the VERY DECENT standard shocks from the agents. By the way the standard shocks are made by a company called KYB who are a very reputable manufacturer.
My 2c worth...

Cheers
Bruce