[oldman]

I have to pass smog, so the cats have to be in the long term codes (which can't be reset by law) take like 500 miles to turn off. 2) I don't see any reason to kill the environment for a few more HP 3) for the M6, the low speed drivability is bad with no cats, for instance, the car can't take 6th gear at 55 MPH with no cats, 4) the car is much quieter with cats, base exhaust system.

[laynlo15]

Staying with the high flow cats from BBK. Not much inside but they are legal so I'll hang with them. I don't like the smell you get without cats and I live in Missouri so at some point it will have to be inspected to get my license. Its loud enough as it is so no cats would make it even louder. I'm old don't care for that anymore.

[Joe's_cool_1le]

No concerns of melting the cats?

[Dysan911]

Originally Posted by oldman

I have to pass smog, so the cats have to be in the long term codes (which can't be reset by law) take like 500 miles to turn off. 2) I don't see any reason to kill the environment for a few more HP 3) for the M6, the low speed drivability is bad with no cats, for instance, the car can't take 6th gear at 55 MPH with no cats, 4) the car is much quieter with cats, base exhaust system.

Originally Posted by laynlo15

Staying with the high flow cats from BBK. Not much inside but they are legal so I'll hang with them. I don't like the smell you get without cats and I live in Missouri so at some point it will have to be inspected to get my license. Its loud enough as it is so no cats would make it even louder. I'm old don't care for that anymore.

Gotcha. I'd rather run cats myself especially for the smell and to help reduce some drone a bit further. I don't understand what you mean though about the M6 and low speed drive-ability. Are you saying 6th is too tall for 55mph? I short shift to the highest gear possible when just cruising around because 1700-2000 is the drone zone and I find I have to jump to 6th quite often without too many issues.

The only reason I don't have cats is I was working with Ted on my tuning and while I had the stock manifolds we were chasing KR and Ted felt it was time to go with OffRoad pipes so I figured if I was going that route I might as well go with LT's.

Car runs great and the tuning is spot on. Plan to get it dyno'd in a week or two.

[oldman]

with CA front cat deletes, there were some resonants (stock exhaust manifolds). Other people saw knock retard but I never did. The M6 with these could not be put into 6th as easily as it was bone stock, but it was not bad either.

With 1 and 7/8 headers (assume 2" to be worst) no cats the engine can't handle higher numeric gears at low speed, it just won't run. So things like 55 MPH in 6th is not doable. Put cats in... works almost like stock... Will not run = 1.6 Honda with 4" fart pipe.

[Dysan911]

Originally Posted by oldman

with CA front cat deletes, there were some resonants (stock exhaust manifolds). Other people saw knock retard but I never did. The M6 with these could not be put into 6th as easily as it was bone stock, but it was not bad either.

With 1 and 7/8 headers (assume 2" to be worst) no cats the engine can't handle higher numeric gears at low speed, it just won't run. So things like 55 MPH in 6th is not doable. Put cats in... works almost like stock... Will not run = 1.6 Honda with 4" fart pipe.

I guess I just haven't really noticed or attempted to run 6th gear at that speed anyway so non-issue for me. Try not to bog the engine as much as possible.

I did recently pick up a Tony Mamo ported TB. A 25 page thread on the ZL1 forum seems to indicate some good results for M6 owners in eliminating the off idle bog, improved tip-in / throttle response and some have even said you can just power through low gears without issue. No doubt based on the results I've read between here and the Corvette forum there will be a improved drive-ability.

[oldman]

without cats, the m6 needs to be at 67 MPH to be happy in 6th, that for many people is an issue. I have a single tip exhaust. My low engine speed drivability does not seem TB dependent I have 3 (103mm, ported stock, stock). It is directly related to having front cats both with CA front cat deletes and with LT headers.

[laynlo15]

If the car is properly tuned there shouldn't be a problem. My stock cats looked perfectly fine when I removed those. If your car is too rich is when you usually see issues with the cats melting.

[oldman]

I hope so, the cats seem to almost glow... LOL.

[laynlo15]

So we finally got the lash cap deal straightened out. Glad I found that post where you guys were all talking about it. Used the Ls7 and ended with perfect preload thanks to Stefano and his tech Matt. Replaced the hard lines once again for about the 5th time. Got the Lt4 pump in the tank and now waiting on my GForce aluminum driveshaft, Nick Williams 102 mm to return from some updating plus I have a new Big Gulp on order from Roto-Fab. So I hope to drive it again when the weather gets better here in Mid Missouri. I will do the boost a pump that came off the Magnuson White car for a little extra help to make sure we have enough fuel .

[Drsagacity]

Good to hear you are making progress brother. I can’t wait to get out with you and watch you run deep 9’s this year.

[laynlo15]

I don't know about deep 9's but somewhere down there

[DapperDan]

Isn't this the aluminum driveshaft that many have had break?

[laynlo15]

I don't think so, not aware of the GForce breaking. I've heard the DSS have had issues. We will find out. I'll have it in tomorrow along with a BMR driveshaft loop.