I thought Subarus were a pain in the neck with a flat four and having to remove half the gubbins on each side of the engine to get to the plugs!
However, my 69500 mile 406 V6 was a bit reluctant below 4000 RPM so I bought (2x4 pack :( ) plugs. Front bank is easy under the engine cover and the coil packs lift off.
But to do the rear bank I had to remove the whole inlet manifold/plenum/throttle body!
Masterpiece of design there Peugeot. Are all V6s like this - I've never really looked.
Good news it that there is now a much smoother performance below 4000 RPM with no sudden wild cam feel at 4000 RPM, but much more torque below.