I run a Tacon Bigfoot 160 with a Castle XL2 ESC (8s max) on my Red Rock Boardshop LaGrange Setup.
I use a formula in Excel so I can plug in different parameters (motor kv / wheel size / gearing / voltage) and it will give me approximate speed in mph.
Here are some combos I have tried and have found the speed estimates to be accurate within 1 or 2 mph:
Motor-- kv-- battery-- wheel-- motor cog-- wheel cog-- ratio-- km/h----- approx. mph
Tacon 160-- 245-- 8s-- 76mm-- 14-- 28-- 2.00-- 51.94----- 32
Tacon 160-- 245-- 7s-- 76mm-- 14-- 28-- 2.00-- 45.45----- 28
Tacon 160-- 245-- 6s-- 76mm-- 14-- 28-- 2.00-- 38.96----- 24
I typically run at 7s and can go 28mph topped out on the flats. Any faster than that and wind resistance becomes an increasingly significant limiting factor. Also, I have no desire to go faster than 28mph. Most of my cruising is around 22mph. Flat out on 8s was way too high a pucker factor for me.
So to answer your question... with the above setup, if you were running your 2 6s lipos in parallel (effectively 6s), you would easily be able to cruise at 23 or 24mph.
Post your wheel size and gear ratio and I will plug in your numbers and give you an estimate.