I've decided to go for a Toda header and a HJS cat. for my B18C6. I just wonder if there are any point in replacing the stock cat-back besides more sound? Do I get any noticeable powergain from it?

 

You will get noticable power gains from replacing it.

The bottle neck just after the cat needs to be removed.

 

I expect the header+cat will yield about 12 hp. Can I expect the same from a better cat-back?

 

Here is a pic of the US cat and a piece of the cat back.


I don't think a cat-back will give you the same results as a header and cat. The exhaust mods will need some sort of tuning to extract the most power.

Maybe ~15hp for a full exhaust system with tuning?

 

A friend of mine is running stock header, no cat and the Spoon Sports cat-back. He dynoed 200hp (+10) and 189nm (+11) of torque. No tuning. With a good header he should reach about 210 hp. Does the cat really have that much to say?? I thought the HJS should give the exhaust almost "free flow"!?


[Modified by Pompiuses, 9:46 PM 1/2/2003]

 

I am not familiar with the HJS brand. What size is the inlet-outlet? 60mm? 65mm?

 

with a decent cat-back, you should net about 5whp+- on AVERAGE. I netted 7whp/5wtq with my T1R cat-back exhaust. Gains can be up to 13+- whp with the SMSP and HYTECH systems.

 

I'm assuming that your Toda header is 2.5" and your HJS cat is also 2.5... so with that here is a picture of a 2.5" with the stock exhaust catback:



Notice the HUGE bottleneck, and here is a picture of a 2 3/8 " Apex Catback with the same cat:



You decide.

 

Skafia that picture man...............