Will the following fit my STI 03-04?
Alpine SXE-1325S 5-1/4"(13cm) Coaxial 2-Way Speaker
Thanks

 

Yes, but why fit a 13cm when with an mdf spacer ring (dead easy to make) you can fit 16cm units in? The mid-range will be much better!

 

You would be better off buying/making adaptors and going bigger for much improved sound.

 

I agree, but struggling to find which ones at the moment, most of the previous suggestions have been discontinued and their replacements seem to have either seperate tweeters, which may not fit. Or built in tweeters which protrude the speaker cone and may be touching the speaker grill.

 

If it's for the front, why not go for components (separate tweeter)? That's effectively what you have now I think.