anyone given the zs back to finance company

as above really
i have a mk2 120 and am going to get (when i find one i like ) a 180
so to give mine back i will need to take mine back to standard so the air fillter, rear lights, stripes, stickers and breaks will need to be returned to standard all the badges put back on but my biggest concern is my exhaust
i have a power flow cat back sytem will i be able to use the 180 exhaust to swap it and get my power flow put on the 180 or can i use only the back box or nothing at all.......

the next thing is how much do these guys know would i get away with putting the mk1 17" on if i could get some and keep the mk2 and if they find something after they take it back can they bill me .....

do i need to have a completed log book at the right intervals for them not to bill me some thing ..

the thing is i need to buy the 180 before to get my 120 to standard but if they say no them im stuck with 2 cars and the misses would not be happy to put it mildly......!!!!!