Most aftermarket ECUs will allow you to set whatever redline you want. However, whether or not the engine will take it becomes the next question, and is it worth it is the next after that.

For the US WRX enginefuel cut is around 7200, and it has been said that it can safely be raised to 7500. I have never heard of anyone blowing an engine from running 7500. Beyond that "people who know" have said that valvetrain work is needed to safely run higher redlines.

As far as whether or not it is worth it...definitely not on the stock turbo, as it usually produces peak HP around 5500 or so. Even with larger turbos peak HP is generally between 6000 and 6500 RPM. So you're not buying too much if you raise the redline on the stock engine, even with a larger turbo. The HP is dropping with higher RPM.

It seems head flow and cams become the primary limitation. And if you're going to work on the heads and cams, it's almost just as well you go for the valvetrain as well, as you wouldn't want to do all that work for just two or three hundred RPM.

STi engines are seeing peak power about 500-1000 RPMs higher than the US engines with big turbos, and I think it can be safely assumed that the majority of that is coming from the top end. Of course AVCS helps here in terms of filling in the bottom end lost with the higher lift cams.

Bottom line is that without some significant work, it's not all that worth it to simply raise the redline.

 

I have been tuning my UTEC. This is how I've been going about it:

Start with the TurboXS map closest to your setup. They have lots of margin in them.

Start at wastegate boost
tune fuel for ~1550F max EGTs
adjust timing until det. Back off 1-2 degrees.
readjust fueling to get back to ~1550F EGT
Thrash it and ensure you don't get det. If so, back off 1 more degree & add slight fueling.


Turn up the boost to the next load site
repeat fueling, timing, fueling, thrashing.

Turn up boost to next map load point...etc...

The car is surprisingly powerful at 8psi when tuned like this. And smoother than if you just start at full boost and tune the 90 and 100% load sites only.

Make sure the stock ECU isn't trying to pull timing. always compare the stock timing to the mod ign timing. If the stock timing suddenly decreases, the stock ECU is detecting very slight detonation that the UTEC isn't. If you see this, start raising the knock thresholds in the Tuner Parameters until the UTEC can detect these same dets, then tune them out.

If teh stock ECU starts detecting dets that the UTEC can't, it will try to retard timing (which it can't do since the UTEC controls timing). Eventually it will get to an Ignition Advance Multiplier that will switch it to the high det fuel map. Then your fueling will get WAY richer. Then it won't see dets, and will eventually get back up to switching to the low det fuel map...etc... your tuning will never be consistent in this case. Plus it's not good for the engine or power to have the small dets in there.

Always make sure you're in the low det map for tuning. You can assure yourself of this by resetting your ECU. It always defaults to the low det fuel map.

Also, your local chapter meets can provide a good chance to talk with people who have experience tuning aftermarket engine management. You can probably also find people with UTECs to compare notes with.