I only have 2 concerns
1 have you got some form of metal mesh in behind the foam so it can't get sucked in
2 I agree with other poster that they may be a bit restrictive
Otherwise they look Hot very nice indeed
As far as cutting is concerned the dremel is the best tool you just need to visualise where you think it needs to be cut and use a permanent marker on the back draw a cutting line say half inch less than you think using a gently does it approach cut along your marked line, hold it rough they in place and remark as nesasary and cut again doing a little at a time till you have it right then us ring a half round fine tooth file clean the rough spots then Finnish wit a chain saw (very fine) rat tail file just stroking the edge hold the file at 90 degree and you will get nice edge you can also get a nice chrome self adhesive edging on E-bay to further Finnish it of.
Probally the most important thing to remember is not to rush the job and to wear protective gear ie gloves glasses and a dust mask because the chrome dust can make you very sick I ended up quite ill and needed antibiotics for blood poisoning the first timeI cut a bear-claw done a couple since with no problems