I have my valves unplugged and they stay open at all times. I have velocity 200 cell cats currently installed. Since the valves are open at all time I know some guys are putting the 4.3 back boxes on the 4.7. Will this pick up anymore sound? since the valves are open is it directly passing through unrestricted or would the 4.3 muffler get me a little more sound?

 

It is marginally louder but not really worth the swap, IMHO, especially with the cats you're not going to notice much different.

 

Stuart
What would the next options be? Your cats are amazing!! Would crossover pipe and or the mainifolds be best? Would like to stage it for cost of possible.

 

X-pipe and exhaust manifolds would actually make the car quieter. Changing out the muffler would be your best bet for more noise (plus less weight!)

 

So even with the valves open changing the muffler would help? Is the 4.3 muffler swap worth it all?

 

X pipe makes it quitter, headers make it louder. What you are probably really looking for us the Vantage S exhaust upgrade. Try that instead

 

I personally don't think it'd be worth it. The cost and effort in my opinion doesn't add up to the little (if any) difference it'd make.



My 4.3L with high flow cats and muffler got quieter when I added headers.

 

I installed a V8VS muffler on my 4.7 and it is much louder and sounds exactly like an S. Lots of overrun pops and it is just what I was looking for. I picked up a used one on Ebay. Do a search and find my thread that has a lot of info in it.

 

Since I run my valves open all the time does it even make a difference with a back box change? I know it's a pas through but would the s muffler still change the sound somewhat?

 

I ran the valves open all the time as well just like I do now on the S muffler. There is a fairly large difference.