Im currently thinking about building a high compression 5efte engine It will be running a td04 or maybe even a td05 if it comes to it.     My question is,  Do I build a high compression or low compression engine?     Low compression will mean:     more boost, therefore I will have to buy arp head bolts.  less chance of det, so I can run standard petrol.  Slower spool time so I would have to buy a hybrid/billet turbo.  I will be running more boost so I will have to buy bigger injectors.     High Compression will mean,     I can get away with standard head bolts since i will only be running around 1.4/5 bar.  I will have a quicker spooling engine so I could go for a td05 instead of a billet td04 etc  I can run a standard toyota mls 0.5mm gasket so I will save money there aswell.   I will have to run super instead of standard fuel.  I can keep my current injectors that have just been rebuilt.        What do you think or will a high compression engine wont perform as good as I think?