I don't know if this has been discussed but I purshased the RRM downpipe and had it installed. As everyone knows, the sound is loud so I had a highflow cat put on and the guy told me that it was a 2 inch not a 2 1/4 inch pipe. I measured it and it was, so I called RRM and they told me that it was 2 inch and that the website hasn't been changed. They told me that the 2 inch was the best size for good backpressure and I don't remember reading it on any threads. The website said 2 1/4 inch and I got a 2. I am not ranting or anything, just thought I ordered a 2 1/4 inch. Sorry if this is a repost.

 

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so, what's the stock size? all you get out of this downpipe is a cat-delete? hell, i can do that with a torch and a welder.

 

Well 2.25" would be 2" inner dimension. So it sounds right. So what did you think of the DP power wise?

 

It is 2 inch OD not sure what ID is. Power wise after putting on a high flow cat is nice. I love this mod because you can really feel the pull on the highway.

 

2" OD is about 1.75-1.8" ID. that seems REALLY small for a car that, with the other RRM mods, will be pushing if not exceeding 200hp (crank) in NA form. but if it loves the back pressure so much, maybe thats why the 4g69 seems to have no probs spooling obnoxiously huge turbines with little effort or lag

 

you can feel much more power when there is no CAT on there, but you would not be able to stand the noise. would be fun on the track!!

 

Oh....and just so the thread starter is aware. The stock section prior to the cat is only about 1.5" at most. THAT is the real bottle neck. So even 2" is WAY better. 2.25 is not required at that point.

 

I am aware of that fact. I was just pointing out that it was 2 inch and not 2.25 as stated. I am not putting the product down. I love it!

 

If you have your stock downpipe handy, take off the shielding between the flex section and the cat. You would be amazed at the size of the kink.