Exhaust reduces from 3" to 2.5" - Power loss?

[_BSMM5]

Recently had an exhaust shop do a custom muffler bypass ($180 vs $1200 for a Turner/Soul) I'm very happy with the sound and from what I can tell it sounds identical to the name brand deletes for 1/8th the price.

However, The shop that fabbed this used a 3" to 2.5" reducer at the very end to fit 2.5" tip inlets... At first I didn't mind but now that I've had time to think about it and look at other peoples set up with full 3" to tips it has me wondering.

Does this 3" to 2.5" reduction at the very end of the exhaust cause any lost power?

Even if it doesn't I might just go back and have it replaced with 3" pipe because I'm OCD and want a full 3" exhaust - which also means I'll have to return the 2.5" tips for 3".

[Ickdeep]

It shouldn't cause any power loss. The problem some owners have for power lose with muffler delete is their vacuum lines are plugged correctly.

Got some pics or video? I just got my muffler tips and hopefully going in next week for muffler delete as well.

[_BSMM5]

Originally Posted by Ickdeep

It shouldn't cause any power loss. The problem some owners have for power lose with muffler delete is their vacuum lines are plugged correctly.

Got some pics or video? I just got my muffler tips and hopefully going in next week for muffler delete as well.

I'll take some videos and upload them once I get the tips in. They're supposed to get in tonight...

I've been rocking the single 2.5" pipes sticking out the back since last Wednesday. Looks super ghetto right now.

I made sure the vacuum lines were plugged. They weren't originally and I noticed a large drop in power until I capped them.

[GiddyAssassin]

Originally Posted by jbharshman

Recently had an exhaust shop do a custom muffler bypass ($180 vs $1200 for a Turner/Soul) I'm very happy with the sound and from what I can tell it sounds identical to the name brand deletes for 1/8th the price.

However, The shop that fabbed this used a 3" to 2.5" reducer at the very end to fit 2.5" tip inlets... At first I didn't mind but now that I've had time to think about it and look at other peoples set up with full 3" to tips it has me wondering.

Does this 3" to 2.5" reduction at the very end of the exhaust cause any lost power?

Even if it doesn't I might just go back and have it replaced with 3" pipe because I'm OCD and want a full 3" exhaust - which also means I'll have to return the 2.5" tips for 3".

Interesting... how far back does it neck down to 2.5? I don't know this platform particularly well yet (still new to it), but in most turbo cars it makes a difference from 2.5" to 3".

[_BSMM5]

Originally Posted by GiddyAssassin

Interesting... how far back does it neck down to 2.5? I don't know this platform particularly well yet (still new to it), but in most turbo cars it makes a difference from 2.5" to 3".

I'd say everything behind the rear axle gets necked down to 2.5"... Quite a bit.

I'm probably going to end up welding back in 3" pipe. Power loss or not, it just doesn't really look right.

[allmotor_2000]

Originally Posted by jbharshman

I'd say everything behind the rear axle gets necked down to 2.5"... Quite a bit.

I'm probably going to end up welding back in 3" pipe. Power loss or not, it just doesn't really look right.

Should be negligible... how much power are you pushing?

[KMORGSM5]

Unless you are pushing over 8-900 whp won't make a difference.

[_BSMM5]

Originally Posted by allmotor_2000

Should be negligible... how much power are you pushing?

I'm stock right now, plan on going catless dp + stage 1 within the next few months. Waiting to get some oil analysis before I wreck my feeble rod bearings

[allmotor_2000]

Originally Posted by jbharshman

I'm stock right now, plan on going catless dp + stage 1 within the next few months. Waiting to get some oil analysis before I wreck my feeble rod bearings

It wont' matter at all...

[Dwaynos]

Originally Posted by jbharshman

I'm stock right now, plan on going catless dp + stage 1 within the next few months. Waiting to get some oil analysis before I wreck my feeble rod bearings

Tuning the car will not wear your rod bearings any faster. An oil analysis may not show any rod bearing issues even if you have.

[_BSMM5]

Originally Posted by Dwaynos

Tuning the car will not wear your rod bearings any faster. An oil analysis may not show any rod bearing issues even if you have.

Well.. theres some good news and bad news in that I guess lol.

[Dwaynos]

Originally Posted by jbharshman

Well.. theres some good news and bad news in that I guess lol.

Don't worry about them. I'll be changing mine in month or so and pics will be up on here. You can then judge if they are bad or not.

On a better note, did you get your downpipes fitted?

[_BSMM5]

Originally Posted by Dwaynos

Don't worry about them. I'll be changing mine in month or so and pics will be up on here. You can then judge if they are bad or not.

On a better note, did you get your downpipes fitted?

Started the removal last night and then realized I didn't have the right O2 sensor socket... so had to put it back together... Looks like it may be this weekend before I get to it now :/

[M335]

I wouldn’t stress to much about that because all M5,s already have that bottle neck on downpipes from 3” to 2.5” when it meets exhaust

[BB6]

Originally Posted by Ickdeep

It shouldn't cause any power loss. The problem some owners have for power lose with muffler delete is their vacuum lines are plugged correctly.

Got some pics or video? I just got my muffler tips and hopefully going in next week for muffler delete as well.

When you say plugged correctly what do you mean? I plan on muffler delete and would like to make sure I'm doing it right

[Ickdeep]

Originally Posted by BB6

When you say plugged correctly what do you mean? I plan on muffler delete and would like to make sure I'm doing it right

So each side there is a vacuum line you'll see that the car uses to control the valves within the mufflers. When you take off the mufflers, just make sure to plug them up with something so that it doesn't leak. Owners have reported power loss and its often that the vacuum line wasn't secured.

[BB6]

Originally Posted by Ickdeep

So each side there is a vacuum line you'll see that the car uses to control the valves within the mufflers. When you take off the mufflers, just make sure to plug them up with something so that it doesn't leak. Owners have reported power loss and its often that the vacuum line wasn't secured.

So a plastic golf tee and duct tape, HaHa