I posted this in the other forum but now that I think about it it maybe better suited for this one given it's a chip tuning issue.

Ok quick run down. I'm tuning my engine/burning my own chips. I've gotten pretty far, and I'm pretty much done with the fuel tuning. Timing is another story.
I started with the LT4 timing curve. I have a mini-ram and figured this would put me close to that style of intake. It runs really well. Problem is I get a little poping in the exhaust and I guess what seems to be some back fire. Nothing major but noticable. I can change the timing and it goes away and the car seems to run just as well. Why would timing cause this? I had a SR before and never had this issue when playing with the timing.

Also this base timing thing. I had it at 6* and told the ECM what I wanted the timing to be and even programmed the chip with my base timing so it could do it's math. Well I noticed a power loss. I put it back at 8* and then chaged the chip to reflect this. SO in the end I should have ended up with the same timing. However the performance increase was noticable. Why would the base timing effect it if in the end the overall timing was the same???

 

You're sure it's just a little popping in the exhaust? None in the intake? Changing the timing could give you a better burn in the chamber which means less pop in the exhaust. SR probably has more velocity and probably more uniform charges that light off easier and are more forgiving to timing.

How do you know your fueling is right on? Is it right on where you get the popping? Where do you get the popping?