Alfa V6 - the
Join Date: Sep 2009
Location: United Kingdom
County: Vale of Glamorgan
Scuttle shake is always going to be a factor in the spider as they do flex a little bit, expecially when you go to lower profile tyres and stiffen the suspension at all.
I am no expert, but the bouncy, skittishness of the front does not sound right at all and not easily explained by wheel alignment alone. My car has adjustable height suspension and is very sensitive (i.e. very hard) and therefore you do feel everything and it can bounce a bit on poor surfaces.
That being said, mine does handle nicely and certainly if yours is standard spec springs & shocks then reporting the problems you mention is a concern. Lowering the profile of tyre will have a small effect, as will the rear polybushing, in tightening up the ride.
If you have only uprated the rear bushes alone, could that affect the front's responses? I have mine powerflexed throughout, so cant comment on a rear only job - perhaps one of the other forum guys has the experience?