Gatesys SW20

if anything you will lose performance by the new headers running to hot and without the shields from the standard headers will heat the engine up and oil more, put more heat into the intake piping,
a waste of time and money for 2-5 hp and a little noise

+1
Unfortunately that's what often happens once you start to ditch the stock items, including the header heat shield, and heat jackets on the secondary pipes. Many people also ditch the lower header brace as well that stresses the rest of the system.
And if you don't want it to rust out after a year or so, if you want it to last it should be stainless.
Realistically a well designed full stainless NA aftermarket system might cost up to 2 k
(BTW the stock system is full stainless)
 
And what performance increase could you expect for it?
My guess for all that money and effort on a stock Gen2 motor you might approach the stock Gen3 performance.
 

I recently changed the headers on my 3sge and the stock headers were alot heavier! I have noticed that the engine heats up a little quicker now that the heat shielding is gone but its only just noticable.

My first post. Have 1990 NA MR2 with a standard 1 in 2 out muffler, which has seen better days. Would appreciate advice on a suitable replacement that would reduce (eliminate) the tinny/raspy sound that is apparently typical for SW20's.

"Seen better days" ?
The stock muffler is all stainless.
Unless it is damaged, to replace it just for a better exhaust sound could be an expensive exercise, certainly if you want something that will last. (stainless)
 
 
 

Bit of a hijack, but I heard the JASMA (toms) Gen 2 headers Stainless are quite a good upgrade?
Anyone to confirm or thoughts on this?

I assume they're the same headers used on the 220hp Toms To22 NA MR2. If so, it'd be a good upgrade.

Hmm, might buy them.. ahaha :) thanks Man!

Gatesys SW20
Bit of a hijack, but I heard the JASMA (toms) Gen 2 headers Stainless are quite a good upgrade?
Anyone to confirm or thoughts on this?

FYI, JASMA isn't a brand, it's the Japanese Automobile Sport Muffler Association, so if an exhaust component has a JASMA certification it just means it would pass inspection in Japan
As MR2QIK said, Tom's products are generally very good, they're a factory backed company so would likely be a nice upgrade