I assume you are talking about salary sacrifice. Just make sure you don't go over the $25,000 limit! The problem is that for many people, it isn't $25,000, but a bit less, because of the 9.25% employer contribution. I'm not sure how much of the employer contribution actually counts towards the $25,000 - it should say on your pay slip.
I am now retired, but I know that I had to be careful, and the most I could put in was $46,523 of a possible $50,000 (I was over 50).