I have a flowmaster cat back exhaust on my lt1. I believe it is an 80 series muffler. The car has a 396, D1SC, AFR 210 heads with 1 3/4 long tubes. Is this cat back not letting the engine breath? Thanks Lee

 

I think there are far better options. Will taking it off make 100hp? Probably not. Turbos are much pickier about mufflers than the super charger.

That being said thats a large motor with extra air coming down the pipes. I would def look from something bigger, or dual cutouts close to the collectors.

 

How about a single 3" cut out ? Thanks Lee

 

I'll look at the car tonight. Maybe I'll put dual 3" electric cut outs. Thanks Lee

 

Try it and see. What kind of power are you making/hoping for?

 

The car made 496 at 4700rpm. But after 4700rpm, it had spark blow out. I now have installed a MSD box and bryan from PCMforless is going to re dyno it. I did this combo years ago and I only have 8:1 compression. At 4700rpm it had 12 pounds of boost. I think it may make 550hp. Thanks Lee

 

After this dyno session, I would like to put new pulleys to get more boost. What do you think? What kind of hp do you think I can get out of this? Thanks Lee

 

I think you will run out of blower before you max the potential of your motor and heads.

 

Since the flowmasters are worse than the stock exhaust, I'd say yes, they are restrictive.

 

yes very restrictive! put a cut out on and tune with the cut out open and will prolly see 50hp, a buddy of mine gained 6xrwhp with a d1sc but he is in the 650-700 range

 

I picked up 29rwhp n/a when I had a flowmaster, just by opening the cutout.

 

being blowen and a higher hp application it will pick up more!

 

Thanks guys!!!!! Lee

 

Did your buddy have a single intermediate pipe? If so what diameter?. Was it one cut out or 2?

 

ya he is running slp long tubes into a y then 3" to flowmaster. added one cutout b4 the flowmaster