Here's some advice given by Michael Delaney. I'm sure you've seen him around these boards and he knows what he's talking about.
I know you are new here, but remember, do a search before you post. Chances are, general topics like this have been discussed before. Enjoy!
Again, thanks to MD for the following info.
"there's no point in raising the redline if you haven't changed the volumetric efficiency...you are on the downslope of the power curve if you raise the redline higher with stock components. You like going slower? Secondly, you risk valve float or valvespring coil binding. You like having a piston hitting a valve and the broken valve churning around in your cylinder head making mince meat out of it or a chewed up piston? Lastly, your LS rod ratio of 1.54 does not support going higher and as you rev higher, the low rod ratio increases the sideloading forces of the piston that pushes against the cylinder wall as the piston travels up and down...you like to wear out your rings and wall, increasing vibration & blow-by ... or worst, put a hole through your cylinder wall , getting oil and coolant to mix?
please be my guest and raise the redline...higher rpm = ruin people's motors
The only reason to raise a redline is because you have a cam or headporting that provides for a higher powerband location...the power is still going up, not down, at the increased rpm range. When I went from my ITR intake cam setup in the GSR to Toda B's, I had to raise the redline from 8100 rpm stock to 9200 rpm, since the Toda B cam powerband continued to make power above 8100 rpm. Otherwise there's no point in just raising it, for the sake of raising it on stock cams.
The safe way to do it, is to upgrade the valvesprings at minimum.
If your engine has high mileage, a safe considration is to get the rod bolt stretch checked and replaced if necessary, get the rod bearing clearances checked and replaced if necessary , get a compression test to check the state of your piston rings and whether they need to be changed, and religiously check your engine oil status.
Ideally, you would get a longer forged rod to increase the rod ratio but this is for race only engines, for people who can afford to have an added deck height spacer welded onto the block to allow the longer rod to fit. Alternatively you can swap the crank so that it has a smaller stroke...this also would raise the rod ratio.
Swapping for sturdier rod bolts fitted to the correct stretch spec would also be wiser minimum safe move.
The only 2 ways I know to get a higher redline is by ECU reprogramming (chip, Hondata, Power FC, AEM EMS,etc.) or getting a Shogun Power Tuner."