im currently running a garbage ebay header with a 2 inch press bent exhaust. im switching to a smsp replica header and a 3 inch or 2.7 inch press bent exhaust and im going to switch from a sri to cai. do i have to et a retune right away after i get these parts installed and is it safe to go full throttle untuned?? how big will the gains be?

skunk2 stage 2 cams
skunk 2 springs and retainers
ferea valves
golden eagle valve guides
440cc injectors
blox intake manifold
golden eagle ls/vtec conversion kit
4-1 header(ebay)
ngk plugs
eyden oil catchcan
JE 12-5-1 pistons and rings
goldeneagle crank support
act stage 1 clutch
crome ecu
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Yes, you should get it tuned. Going from a 2.0" exhaust to a 3.0" exhaust with a decent header could make your A/Fs lean at full throttle but this depends on the tune you are currently running.

If it were my engine, I would not risk it.

As for gains, once you get it tuned, you will know the difference.

 

So now these are available too?