Saab 93 (2005) - HELP :(
 

Hello, im new to this forum... i hope i can find some help...

Okay, to begin with, i have to say im not that much into cars, i have a wide range of understanding but not into many details, anyways, my car is the Saab 93 (2005), i think its an "Arc", 150 HP...

So far i have installed an amazing chip, by "Maptun" it has added 75+ horsepower to the car, i got new spark plugs , regular platinum spark plugs for the "Aero", a K&N Air Filter, and many other modification for its appearance.

First of all, im thinking of getting "HKS - Iradium" Spark Plugs, many say they are the best, but some mechanics told me it wont work for my car so what do you think ?
another thing is the Air Filter, should i get a new HKS filter instead of my K&N one ? the HKS filter is the Mushrom one that is colored, it comes with its base and adapters... also some mechanics told me it wont be good because many reasons firstly because its not covered such as the filter i have now, which is the original box (Base), they told me it would get the Hot air from the engine and thats not good... i have no clue if thats true...

As for the chip, the car is extremely better now and im really happy with it.... its so powerful so i wont change anything as it also cost me some money...

it would really cost me a lot to get headers for my cars, a new exhaust system, so i decided to visit a exhaust specialist and told him what i have in mind, the perimeter of the exhaust is 55cm , im gonna install the 63cm one, after the catalytic converter (We call it "Catalyzer") im gonna install 63cm stainless steel pipes and at the end there will be the "Box" (I have no clue what is it called :( ) its also stainless steel with 2 openings, that guy will take some measurements and the pipes will be created just for my car to be exact and accurate, is all this right or it could be wrong ?

i wanna also install a "Damb Valve" as for the noise will significantly increase and become much nicer...
Also a Circule Earth, it has to do with the battery of the car and it improves the overall performance of the battery...

Im also waiting for my Aero Kit , it will arrive really soon... it includes , Bumper, skirts, spoiler and all the kit...

I would really appreciate a reply, im really lost... and if someone is gonna reply plz include why and how....
Thank yoouuu soo muchhh ....