i always jump in and put my .02 on the cut out issue. on na and nitrous set ups i have always seen .1-.2 reduction in ET with a cut out. never really tried it with the turbo but i saw 60hp on the dyno with a cut out. everyone knows turbos love open exhaust though.

here are my pre turbo results >> https://ls1tech.com/forums/showpost....8&postcount=11

 

richard,
I gained .3 tenths with no cats, that was back to back weekends! the only thing that changed was that I cut my cats off!

 

You've given me hope! I just ordered my cut-outs this morning, hope to have them put on within the next 2-3 weeks. Gonna order the O2 sims later this week. Just started my other part-time job yesterday, gotta start getting some mod money!

I'm beginning to think that my cats might be getting clogged-up. I've got 62,000 on my truck. Also, I ran my cam without tunning for about 4 months and my exhaust smelled really rich the whole time. What do ya'll think?

I plan on getting those straight-through cats by dynomax soon.

 

no cats sound Awesome on the truck, i can definatly tell a difference in the fuel mixture, smells extremely rich! When I get the time i need to put the wideband o2 back on & look @ my afr. I would bet it has changed when in pe, which leads me to believe that my tune was off with the cats on. If i am not mistaken the wideband is oxygen saturation, which would definetly change with the increased hydrocarbons.