Question on vacuum hose unplug
 

When I got the car I was kinda disappointed how quiet it is before the valves open at about 3800rpm and the unplug mod caught my eyes.

I unplug the hose on the left side today, and the car is noticeably louder below 4k rpm. I can't seen to unplug the other with just my hands, I will try again with some proper tools. Today is only the first day, and I am beginning to like how it sounds now.

Now the question is this: is the unplug mod identical to the side muffler delete(bypass) sound wise? I studied the service manual and in theory they should be identical, except of course the weight loss by removing the heavy side mufflers.

I am on the fence if i should continue with this, or change to the center bypass instead.

Somewhat related question: Where can I get a copy of the service manual?

Not identical. The vacuum controlled flapper opens an additional path which bypasses the side mufflers but some exhaust gases can still pass through them. IOW, there are two paths from the headers to the center muffler; one through the side mufflers and the other direct.

With the side muffler delete that path is obviously eliminated so all exhaust gases are channeled directly to the center muffler.

Make sure to plug the hose-side of the vacuum lines after you disconnect them or you'll create a substantial vacuum leak in the system.

Alternatively you can just disconnect the PSE solenoid valve itself, but you have to take off the engine covers to get to it.

That is a good advice. :eek: What should i use to cover the hose?

I bought two short stainless steel set screws (proposed by an RL member) and after pulling the hoses off, just put the set screw in the middle, and reattach the hose and you're all set.

In that case is there a difference in exhaust path between the BBi side delete (without valves) and the TPC side delete?

Do you find a noticeable difference in sound/noise with hoses disconnected? I've had my SW bypass on for two weeks and yesterday disconnected the hoses and didn't think I could hear a great difference below 4000rpm when the valves would normally be closed? It also slightly bugs me that the PSE button is now defunct. Does that seem crazy in a $150k car?? Not sure if I will reconnect hoses??

For me this is my observation. Take note I do not have the SW bypass.

Below 4k rpm, noticeably louder, especially about 3-4k rpm.

Above 4k rpm, PSE button doesn't work anymore (always engaged), otherwise no difference

Sorry, I'm not that familiar with those aftermarket systems.

Thanks Mike!

Update: I just came back from a trip and today I unplugged the other valve.

The car is much much louder, especially when it drones from about 2.5k to 4k rpm.

My question: Does the side muffler delete sound like an louder(!) version of this valve unplug?

Side muffler bypass pipes are significantly louder than just unplugging the vacuum lines.

Make sure you plug the unplugged lines of you leave them disconnected if you don't want a vacuum leak.

J-Pipes that remove the side muffler aren't a whole lot louder at WOT than a center bypass. It is louder at start-up and at lower RPMs. There are still some gases that enter the side mufflers even with the valves forced open. When you delete the side mufflers you basically have no muffler, so it's a bit louder. There is significantly more drone, although it's not at a particularly annoying frequency. The problem I have with the J-pipe and OEM center muffler option is the resonance and vibration I get through out the chassis when driving around town.

For those that have gone the side-muffler delete route, what's the cleanest way possible to remove the vacuum system/lines for the exhaust valves.

I'll be doing this hopefully this weekend.