the main reason i think you will find is that you can legally only have a na 13b in a bug in oz. you can have a 12b turbo but not the 13 as its above the allowable limit. although saying that if you can find an engineer willing to sign off on it it is possible but good luck.
the reason everyone uses the subaru is its also a flat 4 and fits quite well
“We all pay for life with death, so everything in between should be free.” Bill Hicks
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