Cars:- SCX vs Scalextric

Before I start, I should mention that all 4 of my Scalextric cars are (probably) over 15 years old - and the last time I had a Scalextric set IIRC it was Triang and Magnetraction hadn't been thought of yet.

The secondhand Scalextric set I bought a couple of months ago came with a pair of 1990s F1 cars (Williams Renault/Benetton Renault), a Laguna BTCC car and a Megane rally car (the set was Renault branded). The set had had little use and the first time I used it I didn't even bother cleaning the rails, so the cars ought to be barely run-in. The F1 cars aren't too bad on the track, especially since I fitted silicon tyres, but the two saloons tail-slide all over the place and are noisy. TBH I was reasonably happy with it all and I thought that if I put some decent tyres on the saloons all would be fine.

Then yesterday I thought I'd start adding to my collection of cars. I bought the SCX Morgan Aero 8 and Porsche 997. To say they blew me away is an understatement. If anything, the magnets are too strong! These two cars lapped over 1 second quicker than the Scalextric F1s straight out of the box!! Has slot car technology really improved that much over the last 15, or so, years? OK, so the SCX cars aren't perfect but they are far better than I had expected. I can't wait to get another pair now. (I want the Talbot Sunbeam Lotus and a mkII Escort next, but I've got a seven week wait for them) My "wanted" list is something like 60/40 Scalextric/SCX, but now I may have to change that and make it more SCX-biased.

Now, I'm loathe to give-up on my Scalextric cars - particularly as the plan was to have plenty of cars so that I don't get too bored with the whole slot car scene too quickly. My Scalextric magnets do still have some "pull", but nowhere near the same as my new SCX cars. So..... Can I get stronger magnets for the Scalextric cars? Or are they likely to just need new standard ones? Do the magnets deteriorate with age, even if the cars don't get much use? I've seen magnets on eBay, but haven't yet taken much notice of them. Any recommendations of good ones, or ones to avoid?

Actually, the SCX cars came with the magnets in the down position and I've adjusted them up. I tried the cars with no magnets and they were worse on the track than the Scalextric cars.

TIA
Stuart.