I run a Aerocharger 66 race gas kit on mine and LOVE it!! No issues at all. Don't have an intercooler either. Any turbo will have "lag"...there is no way around it (in my opinion) due to the mechanics of how a turbo produces boost.
My experience is this....I have ridden both the BD pump gas (running 7.5 lbs) and my Aero race gas ( running 12 lbs) on the same day and in the same conditions. This was at 8400 ft elevation. I would have to say the "lag" is identical on both sleds due to the Aero turbo spooling faster. There was a big difference in power though, with the race gas setup having alot more. I would estimate the lag at 1 second. Once you ride it a while you dont even notice it at all.
Now if you want to experience "no lag"....ride a Carls big bore 860 sled. I rode all 3 on the same day. Both turbo setups had huge lag compared to that, as throttle response was instant on the 860.
As far as people to deal with on here... I have heard good about Code Red and Boondockers as well. Due to my personal experience, I would recommend Silber Turbos for the Garret setup and Turbo Doc or FasTrax Motorsports for the Aero setup. My personal experience with all of them has been outstanding! The only one i personally stay away from is HM Turbos due to a bad experience.
Thats my 2 cents worth....hope it helps.