I gather some info from the Japanese manufacturers on their performance parts.

Most claim 10-13 HP gain from their cat-back exhaust system.

High flow cat gets 5 HP.

Tubular Header gets 4-7 HP

Stock ECU reflash with new map: 6 HP (12.3 a/f under full throttle)

Below are the weights of the cat-back exhaust sytem:

HKS: 20.1 kg (44.3 lbs)
Greddy: 15.9 kg (35 lbs)
Autoexe: 18.2 kg (40 lbs)
FEED: 18.5 kg (40.7 lbs)
R magic: 16.6 kg (36.7 lbs) (13 HP gain)
RE Amemiya:18.1 kg (39.9 lbs)
Knight Sports: 17.7 kg (39 lbs) (11.5 HP gain)
JIC stainless: 17.8 kg (39.2 lbs)


Chuck Huang

 

I see the GReddy is the lightest but has no HP gain beside it. Is that because there is no gain, or is it because they don't claim, or haven't yet claimed any gains?

 

There is about 8ps for the RE Amemiya and someone said 7kw for HKS???

 

No claim from the manfacturer.

Chuck Huang

 

When I strapped my Greddy on I saw no HP increase (actually a 3HP decrease, but thats small enough to have been weather, temp, or anything else).