lol ok...sense of humor bypass... thats funny...

 

LOL Q&Q don't call my XKR a minivan...

 

there you go

 

Dude thats one polished turd and my DREAM XKR!!! LOL

 

I think he meant a four stroke.

 

The difference, is the catalytic converters and mufflers are like many small objects stuck in the hose, they will restrict the flow.

Changing the catalytic converters and mufflers depending on how it is done is not changing the size of the hose, but rather removing blockages from the hose.

Exhaust gas velocity is important, but say, passing through a small hose filled with sand glued in; the sand will impede flow, and although it may temporarily raise velocity through the sand, velocity, by means of lost force, will have been lost in the passage through the sand.

In an ideal world we'd be able to change the diameter and length of the runners live, and the same for the piping to the exit.

 

If you significantly change the exhaust backpressure characteristics on a 4.2L X150 without making corrections for it in the engine tune, it will lose some power and throttle response.

This is just how it is with the overly complicated engine management in these cars.

On an old-school carbureted engine, or a more basic EFI setup which only monitors a few basic parameters, then reducing exhaust backpressure will make more power.

But that is not the case on the X150.

 

Thank you thank you thank you Cambo! That was the answer I was looking for! I'm 90% certain my plan moving forward is new cats and a engine tune

 

I install cutouts about 6 months ago. They work great. Stock sound when you want, press a remote button and they open up sounding like a beast!

 

Thats pretty awesome. Thanks for posting a pic so I can understand it better. Do you notice any performance gains when in open positoin?

 

No performance gain, just the exhaust beast sound

 

I am very much a novice but I do love exhaust/engine noise so I will chip in. First, the problem with the XKR coupe is the fixed windows in the back. If they could be put down, you would seriously get twice the exhaust sound in the car. I pulled mine out for tinting and it was devastating putting them back in. I take it that this is because the exhausts sit closest to those windows and quite a bit farther away from the driver's window. Heaps of people outside of my 5.0 XKR (x pipe resonator delete) who would comment on how loud it sounded, but to me inside I would only hear it super loud if I had a wall beside me and the window down. In the F type on the other hand you are sitting a lot closer to the tail pipes, as well as a few other tricks, making it much louder inside the cabin.

I suppose that Freedom's cutouts are putting sound out right underneath or at least a lot closer to the driver, so that will be coming up to the driver's window, hence fabulous sound.

I wouldnt do the resonator delete in the 4.2. The 4.2 has an awesome throbby staccato sound, and I think you'd lose that and get an italian howly noise without the resonator. In the 5.0 it doesnt matter so much because it is howly to start with.

One last thing I have done in the F Type is to put BMC air filters in, and take the engine cover off. You then get the induction noise from the front. So in mine, I am getting supercharger whistle at medium revs, then the exhaust drowns it out until it gets to high revs when the supercharger fairly screams, but really that is only when I get it up over 5,000RPM which isnt often and obviously not for long. But worth the relatively cheap price of admission.

 

I don't really notice any performance increase at all, just the beast exhaust sounds. The cutouts are right before the muffler, so more towards the rear of the car.

 

When I ran mine without the muffler it sounded like grandpa's 76 Chevy truck with a rusty exhaust and wobegon low compression 350.

 

Got all of the sound I need with the top down and the butterflies open.

 

Exactly. I've not driven the XKR 'vert but I have driven the F Type 'vert and the noise is massively increased with the top down compared to the coupe with windows open, in fact it gets tiresome after a while.

 

Bruce, your car is gone so you can't try this now; but did you ever run with the cover for the spare tire off the car?

 

I shoved an old blanket down there to tame some drone. You'd also be surprised how much the little package shelf that lifts with the hatch does to quiet the noise.

 

Hi, I didnt think of that. I took the spare out of the f type altogether and you get a lot of exhaust noise coming from the back, behind your head, so that might work.

 

So.... not really looking for interior noise. In order to keep the vibration to a minimal from my 2000 watts and two 10 in subs I have sound dampening material in all the doors including the trunk and side panels in the back seat areas. What I want is people to hear me coming and going with a nicely tuned engine sound not interior noise ...

Wondering how many people I've pissed of with this thread. May as well keep the purists blood boiling... lol