Welcome to the forum,
If you are in st,catherines you should stop by the nissan dealership (new one that opened) or call and ask for andy in sales, hes a 350z aps tt with built block owner:D. Anyhow I am sure he will hook you up with all things dealer related.
With regard to shops, I can only recommend a few in or around the GTA.
-JRP (johnston research & performance) has a very nice shop with probably the largest selection of aftermarket performance parts/accessories in Canada. I had a chance to meet and get to know “stavs” at JRP, he is the GM and would be a good guy to speak with. I purchased my Volks + tires from him and could not have been more satisfied.
Call them and ask for Stavs or Steve, I am sure he can hook you up with anything you need.
-Speedstar is great for all things JDM, they will be able to source almost any part you require from japan at a fair price.
I have personally had great dealings with them, and use there shop to perform almost all my minor work. (ie: fluid changes, bolt on mods…)
Albert is a great guy and will do everything he can to keep you happy.
Give him a call, maybe he will let you check out the race cars (s2ks!!! 
)
-Simone performance is another shop, located in newmarket. I have not used there services before but another forum member/350z owner XuperXero speaks very highly of them.
Also, if you are not already a member of My350z.com, I would highly recommend that you join up, then check out our Eastern Canada regional section.
The site is also a fountain of information related to all things 350z.
Hope to see you out and about.
Cheers,
R:D
^Bro, We are supposed to keep that low key!
… heheh