Installed h/c/i, ported tb, longtubes, converter and then had the car dyno tuned. When I tuned the car I had the factory mufflers on it, now I have dynomax race bullets dumped before the axle. I have only driven maybe 200 miles since the original tune. Do I need to have the car tuned again? I don't know if I am just used to the car now or if it got slower after the muffler install. It feels like it does not pull as hard at the top end of 2nd and 3rd gear. Also twice now while driving all of the gauges instantly pegged out and then returned to normal, just like it does when you fisrt turn the key on. The car never actually lost engine power just flashed the gauges. Does that mean anything?

 

I'm intrested in the answers you receive. but it would help to know what your car is and mods.

 

It's going to flow a little better with an open exhaust.
If you really want max performance, yes tune it, but it is probably pretty close.
If the gauges flash while you are driving, you probably have an elec issue.
Are there any codes?

 

I'd definitely have it re tuned if you had it tuned on factory mufflers with all those mods, then went to dumped exhaust setup.

 

check all your grounds and asl look around you headers and make sure there is nothing melting and grounding out

 

I had this same thing happen to me when my alternator started to fail. I replaced it and it never happened again.

 

yes, your gauges shouldnt sweep when you first start it. when they do that it usually means your battery is getting weak.