Hey guys , I'm planning to do some tuning for my car. For the time being , I did the 4-2-1 exhaust only. and I got few questions to ask. For what I know is that I want more initial speed from my car.. Is it so called low-mid speed ? Which means I wan more pick up instead of high speed.. Cause I not gonna do more then 130 normally. Let's say from nought to 100 faster.. cause I really seldom drive beyond 130.

What shud I mod ?
I planned to have my air filer changed , is HKS a good product...