Pontiac Owners Club UK

I may have ruined my car... It's a 3.8 v6 4th gen. It did have the stock 2.5" exhaust on it, but one tail pipe fell off last year and it had big holes in the back box so I put another back box on. It still has the stock centre section, but the new back box is 3". I wanted it a little bit louder and with a bit of a burble. But now it sounds like a new f1 car - kind of rubbish! And I may have ruined the back pressure because it feels slower and uses more petrol. So an all round fail!

I wasn't expecting v8 noise, but I rented a new v6 mustang a few months ago in Miami and that sounded quite nice. But mine sounds a bit like a Vauxhall nova driving round halfrauds car park on a Friday night!

So, other than putting a stock back box back on, what can I do? Can you get bits to put in the centre pipe to make it a bit quieter or to change the tone, and give me some back pressure back?

it dose not need back pressure (that will reduce power output)
it needs the correct diameter pipe to scavenge exhaust gas and maintain the correct flow rate/speed

So it needs a 2.5" one putting back on it then?

for bottom end power, yes unless you change induction, cam and heads to use bigger pipe

attach it to a v8

Bugger. Time to look for a stock one then. Is there a good exhaust I can put on it which would make it go faster? And not ruin my mpg at the same time? (I still have the 3rd gen for when I want to get 12mpg, I kind of liked getting 30+ out of a v6...)

On the plus side, my SES light has gone out. But I doubt that's to do with the exhaust, probably more like the bulb has gone...

I would think magnaflow and flowmaster etc. make improved systems for a V6