i have a 2.5" exhaust system from turbo back, with a "see-through" high-flow ebay cat converter, so it is truely a 2.5" exhaust system.

now, right now i have a major exaust leak between the dp and the cat converter. there is an appx. 3" length of pipe i had to cut out of the DP (long story, dont ask), and this gap resides right after the flex section.

ok, so basically i am running open dp, but here is where my pondering began. since i am running a complete 2.5" exhaust system exhaust velocity remains high, and EV is what matters most, as i recall. so would open dp effect performance seeing how cat back or no cat back, piping remains constant. so no bottlenecking would be present. i would actually think that open dp would help performance due to that EV is at its maximum, whereas with a cat-back the exhaust gases would have time to cool, thus hindering EV.

let me know what you think the results would be.

-dave

bobin' and weavin' in traffic. No other place i'd rather be .



^^^^^EVERYTHING HAS TO GO.

see its not a permanent situation. as soon as i get access to a welder i will fix that missing link in the exhaust system.

i guess the real question i asked was during that time frame while i am essentially running open DP, will it effect the performance of my vehicle in a negative, neutral, or positive way?

bobin' and weavin' in traffic. No other place i'd rather be .



^^^^^EVERYTHING HAS TO GO.

I think running an open downpipe will allow the turbo to spool up a lot quicker, which can be good, but you will notice a loss in torque from the lack of back pressure. Also, as stated in the last post, the hot exhaust gases exitting just below the engine area is not good. I don't have an open downpipe, but I have a setup that is similar to that.

I have an exhaust cut-out just before the cat-converter location. When it's opened, it's pretty loud and has the same affect as an open downpipe. I've noticed there's boost spike from the open exhaust. The boost level will also be higher. For instance, if I set my boost at 15 psi, and with the open exhaust, boost level will rise to 17-18 psi at WOT. Just something to consider.

___________
Kon C

"Sometimes, a man has to do what a man has to do."

bobin' and weavin' in traffic. No other place i'd rather be .



^^^^^EVERYTHING HAS TO GO.