For mag springs go with Tripp Research.
You can buy upgrade kits online but to get the best customer service in the gun industry, call Tripp and ask for Aaron. He is Virgil Tripp's son and will get the correct parts to upgrade your mags!
Tripp Research, Inc.
Call (877)837-9445 and if Shari answers you won't need to talk to Aaron, she is every-bit as knowledgeable and can get the repair parts on the way to you.
I recommend you get the complete upgrade kit. It includes the Tripp hybrid follower and a proprietary spring that is far superior to the music wire springs used in most of todays 1911 mags.
Talk to this company, have them explain why their product is so much better than any competition. When you call ask to talk to Virgil Tripp. He will be glad to discuss any technical questions you may have. Try that with Bill Wilson or Chip McCormick.
Read about Virgil Tripps background. He has a storied history and is indisputably qualified to bring a brilliantly designed product to market.
When you call don't forget to tell them you read about their product on the FirearmsTalk.com forum and recommend they become a vendor here!
If you are looking for 1911 recoil springs, there is no better than ISMI springs.
If you are going to re-spring, I would highly recomend you take a look at the ISMI recoil springs. I like them for the same reason I like Tripp Research Cobra Mags, its all the company makes and when your entire R&D budget is focused on one item you tend to produce a quality product.
Go here and read:
ISMI Gunsprings, Made in the U.S.A.
ISMI springs that incorporate current technology and are competivitly priced with the 'same 'ol" music wire springs from 1890s! And they come with a one year warranty!
"12 Month Replacement Warranty extends beyond just materials and workmanship. We even cover failure due to wear. Failure due to wear is not some arbitrary figure: if your ISMI 1911 Recoil Spring loses more than 0.375 of free length in 12 months it will be replaced at NO CHARGE (no shipping charge when sent by US Mail) regardless of the number of rounds fired."
Any other spring sellers offering a warranty regardless of the number of shots fired?
What I do is change out my spring every year and ship it back to ISMI. If its bad, they send me a new spring. If its good, I have proof that my purchase was worth the effort.
If you still need encouragement after reading the above, call Marc Cosat (800)773-1940 and ask him why you should buy his springs. Tell him you heard about ISMI here on the FTF, and canebrake said hi.
All my 1911s run ISMI springs and Tripp Research Gen II Cobra Mags.