Seagull Extra 260 160-180
 

FTL 52cc Turnigy engine to powerful for this plane?

In a word, YES!! (not too mention odds on too heavy).
At only 70" in wingspan, a DLE30 or 35RA (or equivalent), or even something like a CRRC 26cc should drag it around with authority (the 3.15 hp one - there are two to chose from CRRC). This vid shows a 73" Sbach being flown on a 26cc RCGF motor (I followed his build blog as mine is the exact same airframe - but only green) and it looks more than up to it for sport flying - http://www.youtube.com/watch?v=eP8LZPGBLP0
That said, at an advertised weight of up to 13 pounds, the Extra does look to be somewhat 'portly' for it's size, so perhaps the 30-35cc option might suit best.

I have read a few threads lately and 26 cc doesn't cut it for sports and people have put the Dle 30cc in and are happy with it's performance but I have herd that its still not quiet enough for 3Din I am not sure what way to go sell the motor and buy a smaller motor I only paid $120.00 Aud for the Ftl 52cc new

The DLE30 will drag it around without hesitation, but of your worried still, just get the DLE35cc. As for the 26cc not being enough for sport, that video I posted of a 73" Sbach being flown with a (low power) RCGF 26cc kinda proves it can.
Happy Xmas.

What about a OS FS 200 P ?