both are pretty awesome pipes. I own an Estoril, which DOES have the restriction, where as several of my riding buddies have Technigas, and does not have a restriction. I've been comparing the two, and the Estoril seems to have a more aggressive header and coning design. The only thing is that you have to derestrict the Estoril. Sooo its all about if you want/can hack and weld the Estoril.
The Technigas is super high quality and beautiful. Con is that you have to buy or fabricate a bracket to install the Technigas. Either way, you couldn't go wrong with any of these. oh yea the technigas more expensive than the Estoril.
Food for thought, all the dudes i know who have an a55 Technigas now want the Estoril....