2.25" exhaust

[TiStick]

Originally Posted by Brabs_Weather

I have the 140400 Borla for the nonPZEV Hatch. I think it is somewhat loud, however not as loud in video compared to the FSWERKS and Magnaflow. It does not drone at HW speed, but around town it can get slightly (farty) because the damn DCT shifts to early and often. So in low a gear it can be loud, but my ears are really good. Also have full spare which could allow some resonance under the trunk area.

Think a layer of dynamat under the spare would cure that?

[Brabs_Weather]

Originally Posted by TitaniumStick

Think a layer of dynamat under the spare would cure that?

Was thinking that too...

[dyn085]

I would like to see dyno's showing a loss with a larger system. Typically, going larger will produce diminishing returns, but I can't imagine an actual loss, especially over stock. Our stock setup is right on the verge of 2" maximum flow capacity, so minow bolt-ons and tune would be on the verge of maxing out 2.25". I have nothing against either, I'm simply curious as to how 2.5" could dyno less than 2.25".

[TiStick]

Originally Posted by dyn085

I would like to see dyno's showing a loss with a larger system. Typically, going larger will produce diminishing returns, but I can't imagine an actual loss, especially over stock. Our stock setup is right on the verge of 2" maximum flow capacity, so minow bolt-ons and tune would be on the verge of maxing out 2.25". I have nothing against either, I'm simply curious as to how 2.5" could dyno less than 2.25".

They were probably comparing it on a completely stock motor. I would venture to say that without airbox mods, the 2.5 killed too much backpressure and increased the pumping losses. You have seen that modding airflow makes the smaller exhaust a limiting factor, so going too large on the exhaust could make the smaller airflow a limiting factor. I have no doubt that the 2.5 produced more hp/tq vs. OEM, but it might not have outperformed the 2.25 vs. OEM

[Sonic_HedgeHog]

It's gotta be solely exhaust without any other bolt-ons.

[Bwill9886]

Originally Posted by Sean05

Me too let me talk to them again and see if I can get any dynos or flow tests; but it makes sense because its smaller it doesn't have anywhere to go and keeps it more compact and hotter thus getting pushed out faster.
Edit: keep in mind borla and magnaflow test with stock headers so it may change if you add a header but one I add my Cosworth if
I chose to do so I'll dyno an see f I can crank out any more with a 2.25 exhaust.
I'm just veering away from custom and went with someone I knew fit. My 05 TruBendz was horible fitment problems till I fixed it. And it was a nightmare fixing them to the point after it was fixed I didn't want it anymore.

That would be great. That's a good point on the header as well.

That's sad to hear about TruBendz kit for the 05. Most guys I've heard using them haven't had such a bad experience. Hell, I'm hoping they or someone comes out with a stainless piping kit so I can change out the crappy stuff I have on now!

Originally Posted by dyn085

I would like to see dyno's showing a loss with a larger system. Typically, going larger will produce diminishing returns, but I can't imagine an actual loss, especially over stock.

That's what got me as well.

Originally Posted by TitaniumStick

They were probably comparing it on a completely stock motor. I would venture to say that without airbox mods, the 2.5 killed too much backpressure and increased the pumping losses. You have seen that modding airflow makes the smaller exhaust a limiting factor, so going too large on the exhaust could make the smaller airflow a limiting factor. I have no doubt that the 2.5 produced more hp/tq vs. OEM, but it might not have outperformed the 2.25 vs. OEM

Good point.

[Sean05]

forgot to post back have the magnaflow with steeda intake now and it does really well(older mitsu eclise gst couldnt pull away from me those made 210 hp stock i thought it was a regular one and at the light i heard psht ) . I'm gonna be fabbing up a test pipe for my crappy secondary cat can decide on doing a step2.25" like the rest of the exhaust down to 2" at the connector or 2" all the way since the front muffler was made to fit the exhaust? i've got 6 years before i have to smog again but id like it to be reversible if i get pulled over and get sent to a ref