I have just finished break in on the my 12 tup evo 2 and have the following qs.....

1. engine is running ok. but some guy at the track who was helping me tune the engine played with the mixture needle. How can i bring it back to normal factory setting ?
2. what tune pipe should i use for this and where can i get it. i had a rd logicss turbo 2 which was damaged. so i am using a skyline 7.2mm right now.
3, the engine came with a small brass pc. (collet) that sits below the fly wheel. but we used the one supplied with the kit . is this ok ? or should i switch.