Koni or Bilstein ? Options

[Fazasport]

I am looking to replace the rear shocks and front strut inserts on my 1970 914. I will be using the car for tours, rallies, spirited driving and maybe an occasional Autocross not for track work. I am interested in a firmer ride than stock but not a harsh ride. The car does not have front or rear anti-roll bars currently.
If choosing between Koni or Bilstein which would provide the LEAST harsher ride quality?
I will also replacing the rear springs. With that in mind, should I stay with the stock 90lb springs or substitute that 100lb springs from the 914-6?

[Jack Standz]

We too are running Bilsteins all around, 100 pound rear springs, stock 911 front and stock 914 rear sways bars, raised spindles by 19mm with turbo tie-rods and stock 911 torsion bars. Our car is lower than stock and we run 16 x7 front and 16x8 964 wheels (D90) with 185/50 front and 245/35 rear tires.

When first driving this combination (with new control arm and trailing arm bushings), it was awful. Very harsh. Did not like it. Now after around 3k miles, it’s much better. Street only, so maybe next time less rear spring and softer torsion bars.

However, the current plan is to restore our ‘72 to very close to stock, but with the addition of front and rear 914 sway bars, leave spindle height alone, stock 4 lug Mahle wheels, etc. Already have stock rear springs and shocks/struts all around, wheels, sway bars, etc.

[Fazasport]

We too are running Bilsteins all around, 100 pound rear springs, stock 911 front and stock 914 rear sways bars, raised spindles by 19mm with turbo tie-rods and stock 911 torsion bars. Our car is lower than stock and we run 16 x7 front and 16x8 964 wheels (D90) with 185/50 front and 245/35 rear tires.

When first driving this combination (with new control arm and trailing arm bushings), it was awful. Very harsh. Did not like it. Now after around 3k miles, it’s much better. Street only, so maybe next time less rear spring and softer torsion bars.

However, the current plan is to restore our ‘72 to very close to stock, but with the addition of front and rear 914 sway bars, leave spindle height alone, stock 4 lug Mahle wheels, etc. Already have stock rear springs and shocks/struts all around, wheels, sway bars, etc.

Jack Standz - My '70 has 4 bolt 5.5" wheels with 195-65-15 Michelin Defender tires, I will probably change them out for `85-70-15 Vedersteins at some point. Also down the road I may add factory 914 front and rear sway bars in order to reduce roll on the twisties.
You mentioned that you have stock rear springs and shocks on your '72. Does that mean Boge shocks and 90 lb springs?

[Jack Standz]

We too are running Bilsteins all around, 100 pound rear springs, stock 911 front and stock 914 rear sways bars, raised spindles by 19mm with turbo tie-rods and stock 911 torsion bars. Our car is lower than stock and we run 16 x7 front and 16x8 964 wheels (D90) with 185/50 front and 245/35 rear tires.

When first driving this combination (with new control arm and trailing arm bushings), it was awful. Very harsh. Did not like it. Now after around 3k miles, it’s much better. Street only, so maybe next time less rear spring and softer torsion bars.

However, the current plan is to restore our ‘72 to very close to stock, but with the addition of front and rear 914 sway bars, leave spindle height alone, stock 4 lug Mahle wheels, etc. Already have stock rear springs and shocks/struts all around, wheels, sway bars, etc.

Jack Standz - My '70 has 4 bolt 5.5" wheels with 195-65-15 Michelin Defender tires, I will probably change them out for `85-70-15 Vedersteins at some point. Also down the road I may add factory 914 front and rear sway bars in order to reduce roll on the twisties.
You mentioned that you have stock rear springs and shocks on your '72. Does that mean Boge shocks and 90 lb springs?

The '72 still has the shocks/struts/springs, etc. it was born with, but this car is a project and hasn't been driven for years, hence the restoration. Don't know the brand or rate, but won't be using them anyway. They will be replaced with new reproductions, but doubt they are Boge.

Edit to answer your original question about adding firmness without harshness:

That's a pretty subjective thing you're asking about. How can we know your perceptions to suggest how to proceed with our gratuitous suggestions? However, all the things we did to our '74 added firmness and, at first, too much harshness. Currently satisfied with its ride after breaking it in, so no changes other than new tires in the foreseeable future. Koni or Bilstein is your choice. Higher spring rates will add firmness, but you decide how much is too much. Higher rate torsion bars will increase stiffness, but at what point do they become too harsh?