What happens if its not the exhaust - I have 205rwkw with a 2.5" exhaust and have run 13.46 @ 105.78 mph and the 2.5" does fine

I wouldn't be wasting money on a new exhaust until you know this is the issue

As i posted before do another run with the exhaust on then remove the exhaust from the extractors and do another run - this will show if there is an issue with your exhaust............

You could just remove the exhaust and do one run on the dyno but this won't give you a true back to back comparison - same day, same conditions, same dyno etc etc

the workshop iv been going 2 is 2.5 hours from my house and being a apprentice i dont have enough money or time off work to drive up there and do consecutive dyno runs otherwise i would and being my daily it makes it pretty hard just leave the car up there for weeks to, so going to do the exhaust and see what happens.

i would also like to know what you have done to your car to get that much power and still hav a single 2.5" exhaust? and have you ever tried a bigger one to see if gain or loose power?

exhaust is done and feels as tho it goes better havnt put it on the dyno yet but hopefully i will in the next few weeks

Had the car retuned twice now second time changed to sct went back to the standard inlet manifold and now makes 172rwkw so could have made more if I'd held onto the plazmaman plenum but oh we'll. now contemplating diff gears and turboing it as I have a new daily.

Hey guys I'm a bit late to the party. Good to see you got it sorted. I had the exact same problem as you with my xr6 it was stuck on 160rwkw after getting atomic stage 4 cams about 2 weeks ago .I had an exhaust built a year ago with pacemaker headers and a single high flow muffler set up in the middle an no rear sounded pretty good to but I didn't get the cat done cos I was a tight a**. So it was still stock size exhaust at the cat. I completely forgot about it and remembered the hard way when I went and picked my car up from the tuners with much dissapiontent. Yesterday I just had a new 2 1/2 inch system built with new high flow muffler and 100 cell cat and my gosh I havnt had it retuned yet but the difference its insane. Its so loud though it makes my house shake when im putting it in the garage it Just shows it pays to spend the money on doing it properly first time round. It's amazing how much an exhaust or even one component of the an exhaust can let you down. Anyway it gets tuned Monday so hopefully it's all fixed.