I have been running the stock clutching on my 08 700.... the only changes I make are the weights for different altitudes. My Primary was balanced and all tolerances were dealt with .... the clutch had only 300 miles on it, but the cover bushing was not installed correctly from the factory and it was binding a bit. The belt side-clearance was not set anywhere near the factory recommendations FROM the Factory!...
Once this work was done to bring the primary back to functioning as it should, The belt was scrubbed clean, the clutch faces cleaned and wiped with Acetone after scotch brite ... after every two hard rides.... I have had excellent performance.
I keep my springs changed out at the beginning of every season and at the 750 mile mark regardless of the apparent condition (they are cheap). Run 2 delrin washers under the spring cup in the secondary so that the spring can function as smoothly as possible.
The belt deflection is ALWAYS set properly as well... this little step that can be done with a wrench, allen key, straight edge and ruler is one of the simplest steps to make sure that your clutching is working properly... but most people dont do it even though it is outlined in your owners manual.
Maintenance and initial setup can turn a "dud" into a real performer... I have seen it on Many sleds...
All the "special" clutching in the world will not give you better performance if the clutches and belt are not functioning well.
Also, confused as to the "flash" that you have.... SLP does not use an ECU reflash for the 700 CFi pipe set.
SLP recommends the stock helix, stock secondary spring... their primary suggests their weights (duh)... at 62 grams MTX (which is the substitute for the stock 10 series 58 gram) but they use a slightly softer spring with a finish force of 320 lbs if you use the same compressed height as Polaris (1.19"). IMO.. this is very similar to the stock 10-60 weights and the 14/330 stock spring.... but then, how would they sell you springs and weights if they didn't tell you this. The very slightly lighter spring/weight (slp compared to stock) will give your secondary a little bit more authority to back shift.
IMO.. I really have not found a better combo for the 700 than the stock...
With your SLP pipe, I would imagine that you could use 10-62's and feel the improvement in top end response.
The 11 series weights load the engine up at lower RPM's ... IMO, not a good thing for the 700's (maybe for a flat lander as pointed out above)
Series 11 Drive Clutch Weights
A new series of drive clutch flyweights have been developed and are now available for purchase from Polaris. The new “Series 11” flyweights feature an aggressive shift curvature, and thinner profile. Drive weights are matched within .5 grams of each other and packaged in packs of three.
When compared to a series 10 weight, the series 11 weight has more weight distributed at the beginning of the profile curve and does not tuck under as much as the series 10 weight. Because of this difference, the belt--to--sheave clearance must be checked and washers may need to be added to increase the belt--to--sheave clearance after installing any series 11 weight into a drive clutch that was previously equipped with series 10 weights.
The procedure for increasing the belt--to--sheave clearance by adding washer(s) to the spider is outlined in all Polaris snowmobile service manuals.
When cross--referencing between series 10 and series 11 flyweights, a series 11 flyweight will function similarly like a 2—gram heavier series 10 weight. For example, use a 11--68 when replacing a 10--70 flyweight.
Just my 2 cents
As for gearing... Robbie at Avid-Products.com oulined this easy check/service.
There is a simple test to see how efficient your gearing is. Mark the inside sheave (make a 1/2" wide line in 2 places from the center of the primary out to the edge of the primary sheave) of your primary clutch with a Marks-a-lot (wide black permanent marker) and go riding. After you have gone on a couple of trips, look at the mark. If the mark hasn’t been wiped off, you can gear down and not affect the top speed of your sled as you ride it. We have talked with people who were afraid to gear down, because they felt it might affect their top speed. This is a valid concern, but if you aren’t wiping all the marks off the clutch, then either you don’t have the horsepower to go as fast as you are geared or the top speed of your sled doesn’t fit your riding style. Lower gears increase drive belt life because the normal operating range is moved out further from the center on the primary clutch. More of the belt is in contact with the clutch and is less prone to slip and reduces belt temperature. You will also gain more throttle control at the lower speeds. Your engagement will be smoother and you will be able to get started in really soft snow without digging a hole.