I've had one experience with a Chinese block and it wasn't nice per say. The casting was very soft, when I put some bolts in and removed them, the metal in the block powered away. Would I use one in a pinch, probably, if I wanted some life, probably not. Hopefully yours is different.
If you have a local shop who you trust, I'd have them checked, cheap piece of mind. I bought a new set for a customer, before putting them in, going to test them.
I bought a 99 Savanah donor for all the parts. Blown motor but new IP, sold that to a customer so the van owes me nothing. :p:penguin::cat::wtf::hungover::android:
Sorry for the extra smilies, my daughter did that, :cool:
No engine needs backpressure, IE diesel or gas and especially turbo engines. Believe it or not, you can go too big, but in this case, it looks like a 4" system and that's fine.