Hey machz69, I just installed my 1 1/4" predator 9818 last week and my acceleration has greatly improved and my top end is still good (track only weighs 36lbs.), as compared to my 1" predator that had 144 trail studs and weighed 46lbs. Just yesterday, I was riding with some buddies and one had a 2001 SRX, that he bought this year (all stock and 1100km), and from a 40mph roll-on, we stayed side by side right up to 90mph, only then did he creep away very slowly, I tapped out at 100mph (25/44 gearing). I was impressed with my speed with that track. Do you want to buy a challenger 1", I only used it two weeks (120miles). I think you'll be happier with the 1 1/4" 9818, as I know you still like top end.
Just my opinion!