Time for some improvements - need some advice

Ok Im rapidly coming to the end of my first grow with Easy Ryder, its due to come down on the 24th (merry xmas) sorry no journal, will be next time....after xmas

The grow has gone well, and the yield looks to be reasonable, but im looking to make some improvements to my operation.

Trouble is there are so many that I could make, so what I need to know is what is worth the effort/money and what is not

Below is a description of my current setup, and following that is some improvements I'm thinking of.

Current Grow - 12 x Easy Ryder (AK-47 x Lowryder 2)
Grown in 9 litre pots of Canna professional soil with BioBizz organic nutrients Veg/Bloom with root stimulator

600 watt air cooled sunmaster dual spectrum HPS with 5" extractor system and passive air intake in a 120cm x 120cm x 180cm mylar tent (4ftx4ftx6ft)

Improvements wishlist.....or not ???

- Increasing pot size to 11 litre (?)
- Changing to non-organic nutrients and also using growth stimulators like BioBizz Top Max
- Buying a 600 watt sunmaster 7200k MH lamp for the first half of the grow (effectively the Veg)
- Adding an additional 250w HPS lamp in the flowering stage to up the yeild (850w in total)
-Adding an 'Active' Intake fan to improve ventilation

Please let me know whats worth doing and how much its worth doing. Looking for cost effective improvements basically. I could post up a photo if that would be useful.

Any good advice would be very much appreciated.

I vote first for the MH lamp followed by changing the nutes.
Passive intakes are fine unless you are experiencing problems and that 600 hps sounds fine. If it were my money, I would try to get the best improvement per dollar spent.

i would say go with the added 250 for flowering.. there really is no replacement for lumens... i don't know too much about those dual spectrum hps bulbs that you are using, but if your not experiencing too much stretch during veg using them, i wouldn't sweat it too much.. or instead of getting a mh for veg, you ever think about getting a highoutput t5? i have one of these, and i love it.. great for veg, clones and mothers... i think i would opt for one of them over another mh for veg any day, and just get the 250 for flowering.. heat is gonna be a problem though whenever you add any more lamps though..
those nutes your using sound good, organic really is the way to go from everything i read, although i haven't given them a try yet..
whatever you end up doing, i wish you the best of luck on your next grow m8.. are you gonna be sticking with auto's for the next round as well?

Yeah am going to stick with Auto's I like the turnaround time, plus only one room, and a finite amount of space. The dual spectrums are not MH spectrum by any means, they are just tweaked to have a slightly higher level of 'blue' spectrum output than normal HPS. If the heat becomes a problem Ill just upgrade the outtake fan I guess, all enclosed reflectors anyway. Heres some pic's

The last pic has a 500ml bottle in for scale