I'm in a similar situation and have the same question. I also have the GC kit and the Hotchkis bars. My FG2's are leaking in the front and need to be replaced. Here's what I've found so far:
FG2's: I really like the FG2's and wouldn't mind putting on another set if I could buy just the fronts, but GM will only sell the set of 4. The advantage of doing this is that if I pay for the replacement then they have a lifetime warranty. ~$1,200
QA1's: D&D valves these specifically for the V (as I understand it) and they give 12 clicks of adjustment. This is the option I'm leaning toward but would be interested in comments from forum members running this setup. I know some of you have some specifically valved for drag racing but I'm more interested in turning corners
~$1,200
KW Variant 3: These look great, but it's 2 weeks past the first 2 week release date and I'm really not sure when/if they're coming and I need to replace mine real soon. This is a full coil over so I'm assuming I wouldn't need my GC any more but I'd want to make sure I could still get spring rates similar to the 600/650 I have with the GC kit now. ~$2,000 est.
Apex motorsports/K-sport coilover: Can't beat the price at ~$875 but I can't get spring rates nearly as high as I'd like and the shock is larger in diameter in the front so I couldn't use my Hotchkis bar (without modification to move the bar forward).
Penske and/or Mallett Penske: The high dollar option. I believe there are specific Penske's specially made for Mallett and also some that can be bought through the likes of Drift Caddy here on the forum. I really haven't researched these too much since I'm not intending to spend that much money.
Sachs T2: I believe these are shocks specifically made for CTS-V's competing in the SCCA T2 race class. I saw a set on ebay once and I think Chef here on the forum has a set he's installing on his machine. I have no idea what these things cost.
On a side note, it seems there are several of us who are using the GC kit on our cars that have had the front shocks start leaking. Is lowering the car as much as we are overstressing those shocks?
FG2's: I really like the FG2's and wouldn't mind putting on another set if I could buy just the fronts, but GM will only sell the set of 4. The advantage of doing this is that if I pay for the replacement then they have a lifetime warranty. ~$1,200
QA1's: D&D valves these specifically for the V (as I understand it) and they give 12 clicks of adjustment. This is the option I'm leaning toward but would be interested in comments from forum members running this setup. I know some of you have some specifically valved for drag racing but I'm more interested in turning corners
KW Variant 3: These look great, but it's 2 weeks past the first 2 week release date and I'm really not sure when/if they're coming and I need to replace mine real soon. This is a full coil over so I'm assuming I wouldn't need my GC any more but I'd want to make sure I could still get spring rates similar to the 600/650 I have with the GC kit now. ~$2,000 est.
Apex motorsports/K-sport coilover: Can't beat the price at ~$875 but I can't get spring rates nearly as high as I'd like and the shock is larger in diameter in the front so I couldn't use my Hotchkis bar (without modification to move the bar forward).
Penske and/or Mallett Penske: The high dollar option. I believe there are specific Penske's specially made for Mallett and also some that can be bought through the likes of Drift Caddy here on the forum. I really haven't researched these too much since I'm not intending to spend that much money.
Sachs T2: I believe these are shocks specifically made for CTS-V's competing in the SCCA T2 race class. I saw a set on ebay once and I think Chef here on the forum has a set he's installing on his machine. I have no idea what these things cost.
On a side note, it seems there are several of us who are using the GC kit on our cars that have had the front shocks start leaking. Is lowering the car as much as we are overstressing those shocks?