Re: James/BigAsh 182 Race Car by TDF... It doesn't get much better than this! *Pic He
If you heel & toe properly when you change down, there is little to no additional strain on the clutch/box whether you change at 1k revs, or 6k revs - as everything is matched together. For example, if i change down from 3rd to second there should be no 'jolt' for passengers, it should be all one smooth motion.
If you change down without rev matching, you are obviously putting a massive strain on the drivetrain, which is obviously felt by the passenger when they bang their head on the dashboard. As Tony says, it is like repeatedly dialling in 6k and side stepping the clutch - its not gonna last very long lol.
In addition, by using heel & toe, you can change down at the same time as braking, allowing you to brake later & deeper into the corner, aiding weight transfer and subsequently giving more front end grip when you need it, ie when turning into the corner. Mastering H&T is essential in getting a good lap time imho.
And it makes you french tin can last a little longer