FWIW, I have replaced the studs in my UP pipe with bolts. It makes mounting the turbo with the oil return line on it much easier. It also helps in putting the inlet hose on the turbo.
The turbo is easy to slide around on the up pipe while you slip the inlet on. Then line the bolt holes up with the up pipe and drop the bolts in.
There's a picture in this thread. I'll edit this post with the correct post number with the photo when I get home or just post that one photo here, can't do that from work.
213,000miles 5/2012 ej257 short block, 8/2011 installed VF52 turbo, @20.8psi, 280whp, 300ftlbs. CHECK your oil, these cars use it.
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