Dampening the crank pulley is definitely a good thing, especially to absorb vibration, but in essence like what empire said in most of his posts, a lightened crank pulley at most shaves off 2kgs tops on a singular part which doesnt really make a significant difference on a mild or road spec car. dont get me wrong, 2kgs on a track car makes a shit load of diff, but those engines are balanced, blueprinted and stripped down after the race. Your crank and engine internals are not expected to last 100 000km as a regular street car is usually overhauled.
Its attached via a belt, even your crank has torsion stresses.

simple..

1) you own a workshop
2)ive never heard a bad review of your services means you know your shit and you do a good job.in fact before you even quota a price you always ajak ppl over to discuss what needs to be done and have a look at ur workmanship.

do you dare vouch for the quality of products you dont carry or the services of any other workshop?

lol.. i dont anything from kissing his ass, just speaking my mind. I dont have a problem with a lightened crank pulley, or a balanced lightened crank pulley. The problem is :

tons of aftermarket parts with no history or proven RnD
some are undersized, some are lightened, some lightened and undersized, some with harmonic balancer, some with dodgy looking rubber damper
The question is, do you want to take the risk of running your car with a product with no history or proven RnD or engineering skills?

Who are mythelogy? try googling them, no history..maybe its a proper Engineering house with tons of credentials and racing designs under their belt, but think about it..if they did, im sure it will be plastered all over LYN, ZTH, have their own wiki etc..

Who are Jasma? http://jasmajapan.com/index.php website is jasmajapan, parts made in pahang? 

maddriver can use it in his "stock" wira/satria end of the day he owns a workshop, so if his car gets f***ed, no big deal. Same story with drex, but I got nothing against them. In fact I respect their contribution to providing knowledge in an open forum for discussion. If you followed drex and guans fotopic last time, you will know these guys are very serious and smart in what they do. BUT i will never go to their workshop because I had some bad experience there. End of the day no hard feelings, maddriver and drex business are still going strong irrespective of what I say or my clientele. You just gotta decide for yourself if you wanna put your trust in watever product in the market.

I can honestly say im not a car modding god. but ive worked in a workshop and I have a very strong engineering background. As a part of this online forum, im sharing my knowledge and thoughts, bottom line is its your F**king car and money. I always answer questions as unbiased as possible. Should I change wira to rear disc brake? i tell you the pros, the cons you f**kin decide. Thats what brains are for, to be used

edit : typo

Well said and well written.. i honestly appreciate it

back to the context of LCPs, why do I or others place RnD and proper engineering on a high pedestal when anyone can make a good performance part? Simple, and let me take you up on your extractor story.
I have reasonable welding skills and I previously handmade a turbo manifold out of high grade,heavy gauge buttweld fittings. Was it hard? very. Did it work? perfectly..in fact it was neater and i put in a considerable effort in calculating the fluid dynamics of exhaust gases in an effort to maximize scavenging effect. After roughly a year and a half, a small leak appeared in the weld joint and started leaving toxic exhaust gases. I check my engine bay regularly and diagnosed the problem and fixed it. Speaking to a few other friends, they have purchased aftermarket extractors which had similar leaks and they brushed it off. This is serious shit. If you breathe in the toxic carbon monoxide gases over a prolonged period of time in a confined environment, you will DIE..no doubts, no second chances. Therefore should there be an importance in choosing a quality extractor from a cap ayam one? I would say yes..

What would the average lifespan of an engine be? Lets say 100,000km of hard driving before being overhauled. thats roughly 5 years give or take. Buying a half baked poorly designed part for instant gratification would not justify the possibilities of something going wrong. How would an unbalanced crank react spinning at 6000rpm? Engine malfunction? I can life with that..Could be worse.. does anyone care to educate the general public of these problems that may occur? Ask a mechanic how to increase your HP, he will say get a stroker it, janji laju..what are the side effects? Tada punya, saya sudah buat untuk banyak kereta..modifying is not something you wanna take on without proper research, reputable products and sincere mechanics

Ive seen engine blocks with holes the size of a cigarette box because a bolt worked itself loose and shot out of the block..if it carries enough force it can go thru your firewall and kill you..it could hit a pedestrian and kill him or her..your car could sieze and hit another car, a motorcycle or a pedestrian. I find it rather irresponsible to say who cares when your decisions affect innocent unrelated people. no RnD? who cares! no QA? who cares! no QC? who cares!

I guess its all fun and games until someone takes a chunk of 6000rpms worth of poorly designed crank pulley in the face. would you still care then?

Use a product for a few months and everyones a brand ambassador. Why do we need quality, research, design, maths,physics,engineering when Muthu my trusty metalworker can turn a chunk of steel into a car part? Who cares? Malaysia boleh 

waaa so many things that i kenot brain here. so long story short, change to lcp if you want the engine to shake shake and goes kaboom and pew pew ka?
sorry i is veli the noob.
so best is use stock and dun modifait the car?