Go for G Power, Iridium waste of money.

From personal experience, I'd say that theres a very slight improvement in mileage, but the best thing about these plugs are that they're self cleaning, hence trouble free.

@ ACS ....Good DIY with detailed Pictures, which will surely help other ZMA owners...I wish to suggest a point here...it is because the wires are at tension that the soldering gives way . Try extending both the wires with about 3 inches long EXTRA wires,and you will not get this problem again.The wires have to be properly soldered and insulated...

Most probably CDI connector loose contact...open seat and shake the CDI connector wires, and the problem will go away..

Never do anything without first understanding the reason, cause and effect....

Placing a 0.2mm washer under the throttle needle lifts the needle in the emulsion tube and hence gives a slightly richer AFR THROUGHOUT the RPM range..too thick a washer will cause excessive petrol in intake ,engine bogging,and reduce FE.. to understand the Emulsion tube and the needle's relative position , see the pic below.

Shortening of spring gives more space for the needle to rise as well as lesser tension on the throttle. The lifting of the needle supplies more fuel at medium to WOT .
Experimenting ??? It sure as hell is logical . Now let's see whether your bike understands logic or not . Do post results .
Apart from what psr said , check the air inlet hole in the tank lid .
If going for a 55/60 W h/l it's preferable to have a higher rated battery .
As ashwin said , go for G power .
Thank you sir for the kind words and the input you gave me . Actually the wires can be extended a little bit on stock wiring . I think if the company had used connectors (either male/female or screw on types ) it'd last longer .

That's a GOOD idea...but I am always scared of the connectors developing loose contact ..since large currents go through these contacts and wires ,loose contact is quite possible. It is better to have soldered joints and not get stranded in no where land in darkness, on a rainy day.(they happen that way ..don't they ?) And the most important fact, any one can start the bike by shorting the connector.

Firstly congrats on the fine DIY and its photos. My thoughts are also in tune with PSR's(ref. PSR's reply)(And the most important fact, any one can start the bike by shorting the connector. ) In India the land of experimentalists , theives also do experiments once they are bend on doing. so security is in God's hands, especially in God's own country.

Usually this soldering doesn't give away so soon and is caused if the wire get stuck somewhere and thus gets pulled while turning handle. There was no need to open the screws and cap. Instead just opening the plastic cover and using a small 20W electronics iron would have done the work without need for removing the ignition section.
It is a one off case of soldering getting disjointed. In my joy the lock set is still the factory one after 3.1 lac km and 12 years but till now the soldering has not come off nor the lock is giving any problem. Recently water entry was creating problem and a few drops of engine oil drove away the problem.
Needle raise will create problem as PSR sir has said. For my experiments with jetting and needle adjustment, needle has a great effect on the tuning of bikes. By raising the needle your low end and mid end will improve but your bike will suffer from top end. It will not even cross 100 kph on speedo. So test and see the results. A rich mixture will always make the top end suffer and has same symptom as engine loosing compression. The accelerator feel will also not be crisp and feel disconnected from bike.

This problem is unique to HH Karizma and some CBZ. The wires connecting to the switch are tethered tightly and over a period of time break loose......not every ZMA or CBZ suffers this problem, but when it happens the cause is known.

Now that I have found out which are the wires going to the key I can short them and start the bike if the need arises
Thanx . I posted it in detail so that if someone is in a similar position they know where to look and what to do . The less said about "GODS OWN COUNTRY" the better ! Having a remote lock gives me some peace of mind .
That's what I think.
Even going horizontal is difficult for me . Last day I struggled with the Wheel Jack while trying to position it under my Palio GTX . You can imagine me trying to get my head under the key for a clear view !!

No worries about top end, cause I run on a free flow filter directly onto the carb, hence no restriction and the AFR can be as rich as it wants.
The speed run was perfect and didnt notice any improvement in mid end, but top end felt abit more confident. Then tragedy struck after a corner my slide got stuck and bike was restricted to 4~5k, and thats when I noticed that the mid end had a considerable increase in torque, I liked it so much that the slide being stuck didnt bother me at all.

Heres what I believe, the less load on the resturn spring + ring under needle, helps me to get into midrange throttle position quicker and hence the boost in performance.

@PSR sir,
In the ZMA's carb, we cant properly use an O ring above 2mm, reason being, I tried a 3mm one from my cycle's dynamo, but the plastic thing would'nt lock, so then when I made a custom O ring with a paper clip, which I assume is 1mm, then it fit perfectly and there was abit of play left in the carb spring. Though now I suspect the ring's dia to be at fault. Im also thinking of another mod, instead of putting a spacer, why dont we put the spring under the needle? I understand then the clearance would be around 3~5mm, but if it works then we can try different spring sizes etc to create a suitable output.

When the throttle slide got stuck you had good torque ? ....it is because you are running rich now...when the slide gets stuck the throttle needle no longer goes up and as you open throttle the AFR gets lean....and hence better torque...
My experiments had proved that in ZMA using thicker than 0.3mm washer under the needle actually boggs the engine at mid and returns poor FE..so do not go for anything above this thickness...K&N kills the carb slide and engine eventually.So stick to stock Air Filter.

Yup, thats the funny part. First didnt notice it because wanted to observe if there was any change in high end, so gunned the throttle, but only when the slide got stuck, I was forced to ride at mid end and the torque could be felt. Infact if it were'nt for the slide getting stuck, I would'nt have got the expected feedback from the mods.

And sir, will be ordering a new slide anytime soon, cause cleaning's not working out well for me.

If you have K&N remove it ASAP..it is allowing dirt and the dirt may be locking up your slide.
Proper cleaning of the slide helps in solving the slide getting stuck .

Not K&N, Cosworth. Its a long term experiment, will wait and observe its effects on the engine.
My slide fouled, because I connected the breather to the intake manifold, which I was warned about earlier, but chose to ignore thinking that the breather would lube the slide, but instead the opposite happened.

Me and Aneesh both cleaned our slides, and for both of us the issue has resurfaced. Thats why we were thinking about replacing the slide, heard it was around 650/-.