S4 C is 6sp and 512k. L is tip and 1024k

You cannot flash an L (or M) image onto a C-box unless you replace the flash with a 1M chip.

The L box image will not run in your car if it is manual.

You'll have to use M-box.

Also, your C-box car has a bosch MAF, so you will have to modify the Mbox accordingly.

Also, your C-box car has an older cluster, so you may have to make a few modifications in the CAN bits on the M-box file to prevent various DTCs.

Finally, there will probably be various coding issues involved (cluster and engine).

Then how i can get 1mb chip in my cbox car?
Box i have, 551l allready has manual tuning inside. Jfonz has done it.

I have a c-box without immo, i desoldered the 29f400bb and put the 29f800bb with 1Mb m-box file but don´t start the car.
Do I have to buy a ecu with 1MB or is there any solution? Thank you

I'll try and I'll post the results.

Find a 1M ECU

Yes, different. Also, you can't use ME7.1.1

Also, daz posted a 551k definition recently, that would likely be a closer match to your c. You could try that in your hacked 1m ecu.