2.5 inch downpipe and exhaust for LSJ
 

Hey guys, looking for a 2.5 inch down pipe and cutback exhaust for my LSJ.

As for the down pipe, I'd prefer ZZP but open to all offers. It MUST be catted and MUST have an extra o2 bung. MUST be 2.5 inch as the title says.

As for the exhaust, I'd also prefer ZZP but open to other offers as well.

Thanks!

Edit: also looking for a set of coil overs. Possibly even 2 sets of coil overs for both of my LSJs.

Don't waste your time with a 2.5" downpipe on the LSJ fyi....

I have a 3 inch now, it's too much for the stock supercharger

No it's not....

The stock downpipe is 2.75".

Leave the 3" downpipe on there.

It necks down to like 2.25" at the o2 sensor.

I dissected a stock SS/SC downpipe back in the day.

The dimple at the o2 sensor is not 2.25"... it is simply dimpled. Yes there is a reduction in cross sectional area of the pipe there, but the majority of the piping is 2.75" with a 2.375" outlet.

Regardless of this, the OP should stick with his 3" downpipe.

I've tested all sorts of downpipes on my car. The zzp 2.5" downpipe is a mess. Terrible transition from the flex to the cat. Their 3" downpipe was made much better.

I feel like I'm losing power because of the down pipe and exhaust though. Stock pulley, stock everything

Stock everything? Put a stock down pipe on and be done with it (until the flex breaks lol)

So put a pulley on it.

The bigger exhaust moves the torque curve a bit higher due to being more efficent. If you switch back to smaller exhaust, you actually restrict the engine at higher rpms so it "feels" stronger down low. Put a 3" pulley on there and a set of GM stage kit injectors, it will pick up all that low end you lost and then some, plus gain 40hp up top.

I have 80 injectors. I'm going turbo this winter and I have most of the kit. The cobalt isn't my daily driver and I miss driving it. The cat on my 3 inch down pipe is done for I believe, so just to get the car running again I was considering going back to a 2.5 inch dp and exhaust. When I'm turbo I'm running 3 inch catless

Thanks for the info. This helped me with some questions I had.

You're welcome!

I have Vibrant high-flo header, catless downpipe, magnaflow muffler, was straight piped between but put a resonator back on. Willing to go full stock if someone wants to trade everything.

06 LSJ

I've got everything but a stock down pipe.