Getting traction is different for everyone, depending on what you have & how it is setup. We have been finding that once you have all the right suspension parts on the back (like our stuff)
it just comes down to a little fine tuning to get the traction you need. It also depends on the total combo that you have, so the front shocks, front swaybar, rim width, front rims/tire weight, rear axle housing (and/or CA mounting positions), pinion angle, air bags & pressures, bushing design in CA's, travel limiters, ride height, and a whole lot of other factors including all the regular stuff with the motor/tune/trans come into play for traction off the line.
One main thing that needs to be considered is the instant center on the car. That is where the upper & lower CA's in the rear would meet if you could draw an imaginary line thru them going forward on the car. Unfortunately, the stock mounting points on the top ears of the stk rear housings leaves a lot to be desired. That stk position lets the rear squat hard on a launch, which you need to think of it as the rearend is actually coming up into the car & off the pavement (losing traction). Without changing the housing, the easiest thing to tune for this is to leave the airbags in and run them at a low pressure (like 5 psi) and equal side to side (if using our sway/anti-roll setup). A shock setting more on the stiff side in the rear helps out too. You want to try & resist the rearend from coming up into the car.
Now the best fix for this is an aftermarket rear housing. Almost all of them raised the upper ears approx 1" to 2", which seems to put them in a sweet spot for the instant center. With this setup, the airbags become almost no help at all, since the rearend gets driven into the pavement & separates from the body on a hard launch. You also want a softer shock setting here, to let it separate faster & easier.
No-hop bars are brackets that attach to the stock housing & raise the upper mounting point 2-3". This is more than necessary & can make it hit the tires too hard. Some say it's better than stk & some say it doesn't help at all (for the G-body cars). Now on an older A-body car, they help a LOT & many use them with the stk housing.
Some companies make brackets to lower the mounting points on the bottom of the rear axle. This also effects the instant center & gets it to hit the tires harder. We don't make them because they seem to help most on lower HP cars in the 12's & slower. There are also several side effects that are negative, like a weird feeling under hard braking. We have seem many make it work without them & not have the bad side effects, so we never made them or endorse them. On the G-body's, I would say go with the aftermarket rear housing, or keep the stk one & just stiffen things up & get it to work as-is.
The front end has to help out for traction too. One big thing we noticed on faster cars (in the 10's & beyond), that the old 90/10 settings are too harsh for the added power levels. Going to a 70/30 type setting slows the rise & fall on the front & makes for a nice smooth transition on the wheelie/launch. If this it too abrupt, then you get a short quick wheelie, and then they usually spin & re-hook & look like they are bucking or porposing off the line (on video). It happens so quick, it is hard to see by eye as it happens. The front sway also is nice on the street, but hurts at the track. Anyone running our rear sway says it works great on the street with NO front sway, even with drag shocks & skinnies up front! Definitely worth a try IMO, probably end up leaving it off like others do.
Don't want any kind of pinion snubber either, as soon as it hits, it unloads the rearend & breaks traction. Also seems that around 3 to 3.5 degrees pinion angle is another sweet spot. Less is easy on parts, more seems to put bite into the rear, and would say no matter what, stay in the 2 to 5 range at any et level.
Our lowers that are +1/4" length also help with pinion angle & tire clearance. They add approx 1.5 degrees to the stk setting. One more important thing on higher HP cars is that it helps the driveshaft from being pushed into the trans too far. The splines on the input shaft will twist, no way around that. The problem lies in that when the power is applied, the tires hook, and the bushings in the rear suspension compress, and the d-shaft is pushed forward. If it goes past the part where it has been riding for years at a lower HP level & are twisted, it meets the part that was never engaged & is still straight. This binds up, and unloads the rear & loses traction instantly. This one is a hard one to find, but shows up when the power levels increase. Easy fix is to take the yoke off the trans & take to a machine shop & bore out the old straight splines so they don't hit/bind anymore.
As for the bushings in the rear, the stk rubber is WAY too soft & lets things move around way too much & doesn't transfer the power fast enough. The std "gold shell" poly bushings that have been avail for years doesn't have any way to grease them & have too much compression on them so they don't move easy & bind & squeak (common issue with std poly bushings). Our regular poly setup has less initial compression so they move easier, and all have a grease fitting to make sure they don't bind or squeak.
Our Extreme Duty bushings are made to handle even more power, and still greasable so no bind & squeaks. They have a hard center for practically solid front to back connection, but softer sides and custom design/tolerances that let it move more like a rod end. They give up a little over the std poly for ride quality, but still better than the rod ends would ride on the street.
After that, we have the Ultimate & Insane series arms with oversize heavy duty rod ends (best you can get) that will take any HP/weight setup you want to subject them to. Some use them on limited street use too, but if in the 9's & driving on the street, I would go more for the XD setup (above). These are more for a race-only setup where you need the best & strongest you can get.
Our swaybar helps with traction & handling on 15 sec cars all the way down to an all-out 7 sec race car. Some still think it's for race only, but we actually have more street cars with them than race cars. It will make it handle like never before, and have you grinnin for years to come!
We try to get everyone to set them up neutral at first, especially if not going super fast. That works best for street driving & mild racing. If going mid 11's & quicker, you will need to add a SLIGHT bit of preload to it. Think of it like a line graph with NO preload at 12.0's, and maybe 3 turns if in the 7's. You should be in there somewhere. One issue is no one can find a perfectly flat surface to set it on, so chances are it's off a little from the start. Best to get a feel for how it drives on the street & track, and if pulling/pushing one way or the other, adjust it based on that more than where you think the "turns" are at from neutral. If going too far off original setting, I would say get it to flat ground again & start over. Shouldn't be that far off to get it to work good & go straight.
Rim width in the rear is important too. Finding a LOT more traction on the 10.5 x 28 slicks when going to the 10" (even 11" on some) over what they "say" is OK to run an 8" rim. Not real sure on the drag radial stuff as much, but would say getting a perfect footprint out of rim width is VERY important. Got several guys with the drag radials getting mid 1.2's for 60' times, so I know it's possible & not just blind luck. The stiffer sidewall slicks seem to be preferred over the older soft side slicks too. Makes it more stable down track & not really giving anything up on the launch.
Hope that helps out!
