Hi, i've just got HKS air suction kit, re-amemiya header and amuse catback exhaust for my 2008 rx-8. I've also got full veilside bodykit and wing, and 20-inch andrew baccarat rims.
However, after all the installation, the car seems to go much slower than the standard one. During standard, it could reach 243km/h and 0-100 in 6.7 secs.
Now, my car only manages to reach 186km/h and 0-100 in 9secs.
Is this normal? I know it's heaver but i think this 186km/h and 9secs stuff are too ridiculous to believe.
I've reset the ECU but nothing changes , or do i have to dyno tune the car?
I really need you guys advice here..
Thanks...

 

What kind of 8 do you have? AT or MT?

 

It's M/T. Is this because it's too heavy? Or i need to dyno tune the car?

 

Put back one item at a time to see what the difference is. I suspect it's your 20" rims that are making your car slower.

Start by swapping back the rims first.

 

When you say your car is slower are your compensating for how far off your speedometer is at this point?