Compression - How much is too much?

[adam]

Hi guys and girls,

I've been a long time reader, but first time poster due to never having anything good enough to contribute, but I've got a question I can't seem to find an answer to and it's doing my head in.

First of all, I've got a 4AGE big port motor with 9.4:1 compression ratio. Everything is standard apart from TRD copy extractors and a pod filter.

I've recently blown my head gasket and while the head is off, I'm thinking of adding a thinner head gasket/shave a bit of the head for higher compression and doing some basic port and polishing.

What I'm stuck on is, how much can I shave off before it is too much for the standard ECU?

Installing a 0.5mm TRD head gasket to my current setup will give me roughly 10.1:1 compression ratio, will my motor run okay? How about going all out and shaving 60thou off the head and use the OEM head gasket? This will give me a compression ratio of about 11:1.

I'm planning on purchasing some 256 and 264 degree cams with about 8.35mm lift as well as a standalone ECU, but I'm just thinking, 'while the head is off, why not get myself some more compression?'

I will be running the car on 98 octane fuel at all times and am aware that I will need to purchase some adjustable cam gears to readjust the timing.

Sorry for the long post, but my question in short is, how high can I take the compression ratio before my standard ECU starts playing up on me?

Cheers
Adam