Anybody that knows or can measure the exact inside diameter of the HKS Hiper cat back where it connects to the cat? I know it necks down from a full 3” but I would like to know exactly how much?

Anybody that also knows if the three different versions of the HKS Hiper (i.e. standard, 30th anniversary and the Ti/Carbon version) necks down in the same way? Would they give the exact same performance except for the quality of the materials?

Last but not least which version was in that TPR Magazine EVO8 exhaust shootout?

Thanks,

 

It dosen't neck down where it meets the cat. I might neck down in the resonator.

 

Hmm, I have my system on the car (standard Hiper w/o stainless piping) but as far as I remember it does neck down at the flange towards the cat or test pipe in my case I'll have to check tonight then.

 

I have Hipower and it necks down at cat to 2.65 inches but who cares since I have not seen any difference in power. With Vishnu stage 1 I made 261.8 on DynoDynamics dyno which is about 310WHP on a dynojet. The HKS exaust gets the same WHP as a true 3'' exhaust. I am happy I got it and I love the sound of exhaust. The DYNO doesn't lie and I have seen that my car makes about same horespower as VISHNU turbo back exhaust.

Peace,
Snoop

 

The 3 Exhaust from HKS are the same design, just different materials. The one in the TPR shootout was the 30th Anniversary which is all polished stainless steel (piping and muffler).

I have the Carbon Ti, which is polished stainless steel Piping with a carbon wrapped muffler and Ti Tip.

The Standard Hiper has according to the HKS sales guy I talked to has stainless steel piping and polished stainless steel muffler.