have y8 ej6 with headers and intake with k&n filter so far. No cat due to car being a DX so cat is attached to exhaust mani. Plan on getting my exhaust redone next but have some questions. Would 2.25" be good enough for some gains? Should i stay catless, test pipe, or high flow cat (if that makes a difference?). Also plan on getting a Apexi N1 tip later on.

 

consult your nearest dyno for actual gains. I don't like throwing speculative numbers around. if it's not on the dyno what's the number matter anyway..? will it be faster? meh. maybe, but not much.

i have a similar set up in my EJ6 currently. There was a fairly noticable bump in mid-range torque as measured by my "butt" dyno.

2.25" or 2.5" would work fine with what you've listed. running with no cat smells bad and isn't legal on the streets whether your state does inspection or not. I would encourage you to do some further research, but i do recall reading that the performance difference between a high-flow and test pipe are negligable.

 

Not really serious enough about my motor right now to go to the dyno, i mean come on its a Y8 lol. but yea been reading around and seems 2.25 is good for my motor size. Wont go into the dyno untill 1. I find one in my area and 2. get a z6 head and start building. Yea, does the test pipe help the smell? sucks getting out of my car and smelling like gas for a while haha and yea its not legal but cops in my area dont really crack down on that.

 

Test pipe is basically just a pipe. Same thing as cat less.

 

so whats the point? just another ebay ripoff? haha

 

the point of a test pipe..? you can swap it out when you go to the track, then swap the cat back in to drive home.

 

So i did it and could feel a slight + in Acceleration and the sounds isnt to bad either.

 

You would see like a 5hp gain probably. You probably think you felt a gain because it sounds like its going faster. But maybe you did, who am I to say you didn't lol