Here is a quick and easy way to tune up a Sebring chassis. If you are running on a Carrera or wood track you can replace the standard guide with with a Slot.it guide, part number CH07. This is the Slot.it guide for wooden tracks. Works just as well with the deep slot on a Carrera track. Replace the rear tyres with either Maxxtrac part number M18 or Super Tires part number ST 1301. And remove the magnet.
If you want to add inserts, with some sanding and filing around the back edge of BWA inserts they fit just fine. I think it is the .450 BWA inserts that will work. There are two sizes of BWA inserts for 1/32 cars, it is the larger of the two sizes that work.
Regards, John