My 4x2 reducer was long enough for me to get an easy flange on the 4" end of it. Makes a neat clamp connection onto the RC and keeps it all compact.
For those building or contemplating a new build I would recommend buying one of these exhaust tailpipe expander sets.
Buy one set between 3 or 4 builders living close to each other and it gets even cheaper. Cost is $32 delivered and the set goes from 1-1/8th to 3-1/2".
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It won't expand 4" but will expand a pipe to fit into 4". You can also use it to do tapered reducers. I used some 1/4 flat bar strips as a spacer and managed to expand 4" once but it's not easy. The difficulty is holding the pipe and tool while expanding.
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Available from Sydney. Delivery wasn't the fastest but it arrived and good value for money.
http://www.ebay.com.au/itm/NEW-3PCS-TAI ... 0795719417Hope this helps.
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