Doug's or TTI headers

I'm going thru the same dilemma for my 64 Dart.
Doug's are a bit cheaper if you can get the AZ 20% off deal but the smaller collector and slip tubes bother me. I had hookers on my 68 and never could get the slip tubes to completely seal. they do make for an easier install though.
The TTI's larger stepped tubes, 3" collector, and no slip tubes. tougher install and a bit priceier (no discounts ava.). Also the TTi's are designed for 340/360 ports where as the Doug's where designed for 273/318 ports.
My car is going to be mostly a track vehicle so I'm leaning real heavy right now to the TTi's.

Any solutions for sealing the slip tubes? I'm always up for saving $$

Thanks, Gary